Linux Voice [Issue 2]

Authors Linux Voice

Plaintext

The magazine that gives back to the Free Software community
May 2014
SCARY RASPBERRY PI YE OLDE CODE 114 PAGES
KERNEL ARCADE! HOPPER OF NEURAL
Write your ﬁrst module Build an arcade machine Learn from the creator
ENHANCEMENT!
for the Linux kernel and live your 80s dreams of the ﬁrst compiler

FREE SOFTWARE

NEEDS
YOU
Linux, Android,
JavaScript – jump IT’S EASIER TO
into coding now
and make the world ASK FORGIVENESS
a better place THAN IT IS TO GET
PERMISSION

34+ PAGES OF TUTORIALS
UEFI Booting’s Brave New World
May 2014 £5.99 Printed in the UK

TEXT EDITORS The Editor Wars rage on…
SOLYDXK The thinking geek’s rolling release

ADOPTION DESKTOP

MUNICH KDE 4
Inside the biggest Free Unleash the power of
Software migration yet the tweaker’s desktop
WELCOME

Linux is awesome
The May issue

Linux Voice is different.
Linux Voice is special.
Here’s why… GRAHAM MORRISON
A free software advocate
At the end of each ﬁnancial and writer since the late
1
year we’ll give 50% of our 1990s, Graham is a lapsed
proﬁts to a selection of KDE contributor and author
organisations that support free of the Meeq MIDI step
software, decided by a vote among sequencer.
our readers (that’s you).

T
here’s a lot of renewed emphasis on learning to code, and
No later than nine months a great deal of noise being made about transforming the
2
after ﬁrst publicaton, we will way computing is taught. This is unequivocally wonderful
relicense all of our content under because to many of us, the only way to tackle such subjects is
the Creative Commons CC-BY-SA through Linux and Free Software. And it’s working. At the recent
licence, so that old content can OCR Raspberry Jamboree in Manchester, the many educators
still be useful, and can live on even in attendance were talking in terms we’ve used to describe open
after the magazine has come off source for years; collaboration, transparency, openness and being
the shelves. inclusive. But there was one term they used that I think we as a
community often forget, and it’s a word we try to put at the heart
We’re a small company, so of this magazine; put simply, it’s fun. Learning, for me, has
3
we don’t have a board of always been much more effective when I’m enjoying myself.
directors or a bunch of It’s the fun element that has kept me sustained, and sees me SUBSCRIBE
shareholders in the City of London
to keep happy. The only people
through those twilit hours trying to ﬁgure out how PulseAudio
works. Linux and Free Software is a serious business, a sober ON PAGE 34
that matter to us are the readers and essential cornerstone of computing. But that doesn’t
(you again). mean we can’t enjoy every minute of it.

Graham Morrison
Editor, Linux Voice
THE LINUX VOICE TEAM
Editor Graham Morrison
graham@linuxvoice.com
Deputy editor Andrew Gregory
What’s hot in LV#002
andrew@linuxvoice.com
Technical editor Ben Everard
ben@linuxvoice.com
Editor at large Mike Saunders
mike@linuxvoice.com
Creative director Stacey Black
stacey@linuxvoice.com
Malign puppetmaster Nick Veitch
nick@linuxvoice.com
Editorial contributors:
Mark Crutch, Liam Dawe, ANDREW GREGORY BEN EVERARD MIKE SAUNDERS
Juliet Kemp, John Lane,
Vincent Mealing, Simon Phipps, I’m already working on an easy KDE has always been a tough Discovering that Steve Ballmer
Jonathan Roberts, solution to this month’s coding proposition. But our tutorial on was parachuted into Munich,
Mayank Sharma, Valentine Sinitsyn challenge: prepare yourselves for getting the most from the KDE and his subsequent hilarious
the Gregorian fractal! p96 has made me try it again. p86 encounter with its mayor. p52

www.linuxvoice.com 3
CONTENTS

May LV002
We are all in the gutter, but some of us are looking at the stars
36
SUBSCRIBE
ON PAGE 34

Get coding now!
Android,
JavaScript,
Python – get
stuck into
programming.
52 REGULARS
06 News
Ubuntu for Phones isn’t just
a mirage – it’s coming!
08 Distrohopper
What to put on your
quintuple-booting box.

10 Gaming
Give your brain a treat with
some neural candy.
Speak your brains

MUNICH
12
These pages are a soapbox
made out of Linux.
16 LV on tour
Manchester: home of the new
Industrial Revolution.
Find out what’s behind the Bavarians’ Group test
28
decade-long migration to Free Software Your machete to cut through
the jungle of text editors.
46 Interview
We track down 3/4 of the
Raspbery Pi education team.

108 Masterclass
Control FTP with FileZilla;
control everything else with SSH.
112 On your DVD
Every single graphical
desktop from Mageia 4.
56
YOUNG REWIRED STATE 60
FAQ Dockers: why 62 SYSADMIN 114 My Linux desktop
The kids are taking it’s like VirtualBox, Jon Roberts presents At home with Ubuntu
engineering manager Alan Pope.
over, with code. but more 1337. Linux containers.

4 www.linuxvoice.com
REVIEWS
TUTORIALS
74 76

20 Dell XPS 13 Looking for a new
Linux machine, but don’t want
a heap of plastic rubbish? Step
Bug reports: help make Raspberry Pi & MAME: right this way!
free software better build an arcade machine
If you do it right, getting bugs Play the games of your youth*
ﬁxed can be an important part of without squandering all your
free software development. pocket money. *Graham’s youth

82 86

22 Retrode Dust off your collection
of games cartridges – the
Retrode has arrived to imbue
them with new life.
23 Krita 2.8 Now Windows types
can use KDE’s excellent image
editor. That’s great, but is there
Old code: Grace Hopper KDE: conﬁgure the hell anything new in 2.8 for us?
and UNIVAC out of your desktop 24 PyBorg Your dream of
controlling an underground
How to program on a machine The defaults in KDE are an robot city has just come one
that weighs more than a double- affront to taste and decency – so step closer to becoming reality.
decker bus. ﬁx it and make your life better.

92 96
Code 101:
100

Secure key
exchange
Lasers, maths and
cryptography.
25 SolydXK Based on Debian?
UEFI: The new Python: Draw Linux: Write
102
Yawn. A third way between
world order of patterns with your ﬁrst kernel timed and rolling releases? Now
we’re interested…
booting recursion module
Boot Linux without Write better code It’s not just for angry
26 Books Computing in the UK,
then and now, plus a small dose
Grub or a BIOS. with fractals. sweary men. of Arduino and a huge heap of
Raspberry Pi.

www.linuxvoice.com 5
ANALYSIS

NEWSANALYSIS
The Linux Voice view on what’s going on in the world of Free Software.
Opinion

Steering where you look
The seductive power of boundary conditions can ruin your business and community.

Simon Phipps and forgotten to keep pace with the a non-profit or a for-profit organisation; profit
is president of the expectations of their customers. is an orthogonal concept.
Open Source Initiative
They’ve let the market run away from The process by which this distraction from
and a board member
of the Open Rights them and failed to build new businesses core values happens is subtle, and undoing
Group and of Open around their fans and friends. Instead, the error is hard. It probably happens
Source for America. fixating on copyright infringement, they incrementally as communities pass through
alienate the very people who should be their the scales described by Dunbar Numbers
best bet for the future by treating them as [the theoretical number of people we are
criminals. They may not go as far as chasing capable of forming direct relationships with
everyone with lawsuits, but the unskippable without our brains melting, proposed by

W
hen I learned to drive, my admonishments on DVDs and their like Robin Dunbar to be between 100 and 230].
instructor told me “you steer shout loud and clear: “We may have some of They eventually mistake their boundary
where you look” -- in other words, your money but we still don’t trust you.” conditions for their core values.
wherever you focus your attention becomes At first a community is small enough for
your destination, so keep your eyes on the Open entrepreneurship everyone to have a set of direct trust
road ahead and don’t worry about the stores Open source projects are another case, relationships. As the community grows
at the roadside (or even too much about the perhaps a little more subtle. Entrepreneurs through the Dunbar limit, it becomes
kerb and the parked vehicles). see the word “free” and assume there’s a necessary to define the norms for the
The same principle seems applicable in commons there to exploit for profit. But community, to make it clear to newcomers
other contexts. We’re moving away from a open source only has a commons once a what the values of the community are.
hierarchical, post-industrial society and community gathers -- it doesn’t magically As growth continues, those norms
evolving into a meshed society of peers, arrive the instant you apply an OSI-approved become rules and the frequency with which
interacting in variable roles on their own licence. Moreover, the commons exists only they are enforced increases. Gradually,
terms. That’s challenging established by the collective agreement of its communicating the rules to outsiders
institutions, but sadly they have frequently participants to set aside certain rights so becomes a common community function
“steered where they looked” and made the that collaboration becomes possible. and the ability to do so becomes a
wrong choices. Entrepreneurs tend to be so focussed on community skill. Over time, application and
The big media lobby -- especially the leveraging a free network effect that they explanation of those rules becomes so
movie and music industries, but also book, overlook the actual mechanism that makes important to the community that they
software and games publishers -- is right to it happen. overshadow the original core values.
be concerned about systematic An open source community is an example
infringement of their copyrights by of a group of people choosing to Influence, not control
commercial-scale criminals. But they have synchronise a fragment of their mutual There’s no canned solution for this; it takes a
let their eyes wander. interests, each at their own expense, for the brave executive to step away from the
They have looked so long in anger upon benefit of all involved including themselves. weapons and chart a course for influencing
those crooks, invested so much time and While there may sometimes be a non-profit the meshed society instead of attempting to
money in frustrating them, that they’ve organisation for administrative reasons, an control it. The news that Getty Images is
become fixated on copyright enforcement open source community is inherently neither now allowing free embedding of their entire
catalogue for non-commercial use is just
such a bold, visionary move. I hope we will
“The media lobby alienate the people who should see much much more of that and many
be their best bet by treating them as criminals.” fewer anti-fan lawsuits and copyright-
assignment-based open source projects.

6 www.linuxvoice.com
ANALYSIS

CATCHUP Summarised: the eight biggest news
stories from the last month

Linux has won. No, really. Microsoft to follow Mt GOX, the world’s
1 According to technology 2 strategy espoused by 3 biggest Bitcoin exchange,
analysts Gartner, Android Linux Voice readers has collapsed
has now overtaken iOS as the leading We’ve only been in print for two issues, The rabbit hole gets deeper for the most
operating system for tablets. And this is but already Linux Voice is having an widely used cryptocurrency.
massively significant – the same date effect at the top table of tech. We asked
suggests that in around 115m tablets listeners to the Linux Voice podcast
were sold worldwide in 2012, compared what advice they would give to the new
with 200m in 2013, so in contrast to PC CEO, Satya Nadella, and among the
sales, tablets are growing quickly, and responses was the suggestion that the
Linux is taking the majority of this very company should give Windows 8 away
large pie. Android is estimated to have for free, to preserve the market for the
62% of the tablet market, with iOS on lucrative Microsoft Office package. Lo
36% and Microsoft lagging behind them and behold, it has come to pass, as the
both with on just 2% market share. soothsayers of LV foresaw.

Broadcom releases the Google Chromium Linux Containers reaches
4 source code for Raspberry 5 browser ported to run on 6 its 1.0 release
Pi graphics stack Mir graphics server Linux Containers have been
Much as we love the Raspberry Pi, it The great schism at the heart of bubbling away under the radar for a
isn’t as free as in speech as it could Linux graphics continues, as Ubuntu while now – discerning sysadmins can
be, largely because Eben Upton is a continues to go it alone with its Mir read our take on them on page 62 –
pragmatist and doesn’t particularly display server. It has now managed and now they have reached their first
want to make things easier for the Pi’s to get Chrome running on the server, major version number. Linux Containers
profit-driven competitors. However, which is its intended replacement for X. can be thought of as being a bit like
we’re glad to see that Broadcom, maker Meanwhile, most distros have elected to VirtualBox, except that rather that
of the Pi’s graphics hardware, has use Wayland as the replacement for X. being completely virtualised, they use
released the source code for the Pi’s X is such an old, ingrained standard that the existing kernel and just create their
graphics chipset under a BSD licence. it is taking time to replace it, but the day own userspace, making them handy for
Well done Broadcom! will come, and either Wayland or Mir will anyone who wants to be able to deploy
www.raspberrypi.org/archives/6299 be the new norm. lots of Linux instances easily.

Canonical unveils Calligra 2.8 released
7 manufacturers for 8 KDE’s office suite, Calligra,
Ubuntu for Phones has reached its latest stable
Like buses, you wait ages for a release. You can read all about our
phone manufacturer to team up with impressions of Krita, the suite’s image
Canonical to bring Ubuntu for Phones editor, on page 23, but there’s much
to market, then two turn up at once. more to the suite then that. There’s now
Spanish firm BQ (which also operates support for comments in Author and
in Latin America) and Chinese firm Words, the ability to open hyperlinks in
Meizu have both signed up to produce the Kexi database app, and the usual
handsets loaded with Canonical’s bugfixes. We yield to no-one in our love
swish mobile operating system. We’ve of LibreOffice, but if you’re running a
always liked Ubuntu for Phones, and KDE system you might want to give the
we’re delighted that there will soon be Calligra suite a try as an alternative.
a physical product in the shops. www.calligra-suite.org

www.linuxvoice.com 7
DISTROHOPPER

DISTROHOPPER
We’ve tapped GCHQ’s communications to find out what’s going on in distro land.

Emmabuntüs
Linux for humanitarians.

D
ifferent situations need different
distros. For many users it’s
important to having a solid base
system that’s around 700MB, making it easy
to download. This is usually backed up by a
great set of repositories that combine to give
you access to almost all the software you
need. Other times, it’s really important to
have everything you need installed from the
start. Perhaps it’s going to be installed
somewhere without a good internet
connection, or perhaps the users won’t want
to install software themselves.
Emmabuntüs fits into this second category.

For recycled hardware
It’s designed for older computers for use by There’s so much choice in Emmabuntüs, it can take some time just to get to know the applications.
children. It has bucket loads of software in
its 3.3GB download. Much of it will be Basically, it just has a simplified interface to software (Flash, etc). If you’re looking at a
familiar to most Linux users, but there’s also make it a bit more friendly. distro for older computers to use in a school
a few unusual choices such as OOo4kids. Xfce is a good choice for a desktop given or community group, Emmabuntüs is
This, you probably won’t be surprised to the intended audience, and we like that it definitely worth a look. Even if you decide to
learn, is a version of OpenOffice designed for asks the user if they want a dock at the go with something else, it’s sure to help you
children (http://wiki.ooo4kids.org). bottom, and if they want to install non-free find a useful bit of software or two.

Picore
Possibly the fastest Linux distro on the Raspberry Pi.

T
inyCore Linux is a technical marvel. team have now released a build for the Pi
It’s a full Linux distro, including a called PiCore.
graphical desktop, and it’s only about Compared to any of the other Linuxes for
15MB. However, it’s not the size of your the Raspberry Pi, PiCore is startlingly quick.
distro that matters, it’s what you do with it. There’s almost no lag when opening
The small size of TinyCore allows it to applications even on a non-overclocked Pi. There’s not much software included by default
boot in a slightly unusual way. Instead of It’s a refreshing change from Raspbian, in Picore, but plenty more can be downloaded
loading files from disk each time something which can leave the user waiting at times. from the internet.
is needed, the entire system loads itself into It’s hard to recommend PiCore to people
RAM when the system boots. This results in new to Linux because its architecture does However, experienced Linuxers looking for a
an OS that’s startlingly fast even on modest add a little complexity, and the RAM storage little more snap on their (low-powered
hardware. Modest hardware like, for makes it a little too easy to lose all your files machine) should seriously consider it. After
example, the Raspberry Pi, and the TinyCore when you reboot if you’re not careful. all, it’s only 24MB to download and try.

8 www.linuxvoice.com
DISTROHOPPER

Bodhi 3
Seek and ye shall find Enlightenment.

I
t’s impossible to separate Bodhi and is the lack of Enlightenment-specific
Enlightenment (a window manager). In software. While both GTK and Qt have a
fact, it’s one of the only popular distros large stash of programs that will fit in with
that’s set up purely for Enlightenment, and the look and feel of a desktop, there’s very
so any new user is going to notice this little built specifically for Enlightenment, so
desktop far more than the underlying distro. most software looks out of place. Beauty is in the eye of the installer, and plenty
Enlightenment has some real strong Underneath this, Bodhi is a solid distro of people like the eye-candy of Enlightenment.
points. It’s impressively fast for a desktop based on Ubuntu LTS. Unfortunately, the
with so many graphical effects. We like how Bodhi team have dropped support for ARM decision. If you want to run Enlightenment,
it looks, though some people may find the chips in this release. They found it simply Bodhi represents the best choice for most
default setup a little gaudy with shimmers too much work for too little gain, which is a users. This also means that the Bodhi live
and glows everywhere. The biggest let down disappointing, though understandable, CD is the best way to try the desktop.

Linux From Scratch SystemD vs Upstart vs sysV init
Going beyond off-the-shelf Linux distros. When you turn your computer on, the
bootloader loads the kernel into memory, then

W
hen most distros are released, system. The start of March saw the release starts the init system. Traditionally, this init
system has been a series of scripts that start
you can go to the project’s home of version 7.5 of this book, which guides the
everything running, and enables you to stop and
page and download an ISO. user through the most recent versions of the start servers once the system is fully booted up.
Alternatively, you may be able to update a upstream projects. These scripts (often called systemV init) kept
system that’s already running. Neither of Different people have different takes on Unix systems booting long before Linux was
these is possible with Linux From Scratch LFS, but the two most common opinions are invented. However, two newer systems have
been created: systemD and Upstart. These both
(LFS) because, well, it’s a book. You can read either that it’s the best way to learn about
offer more advanced features than the older
it online in HTML form, or download a PDF. the internals of a Linux system, or that it’s scripts. Loosely speaking, Ubuntu and most
LFS isn’t really a distro in the usual sense just a way to waste days compiling derivatives use Upstart, while most other distros
of the word. Instead it’s a guide for creating hundreds of pieces of software. Here at use systemD and a few still use systemV.
a system that doesn’t need a distro. After all, Linux Voice, we see the appeal of a system Debian, a slow mover in the distro world,
had clung onto systemV up until the start
a distro is really just a collection of software, such as LFS, and it certainly has its place.
of 2014. However, the technical committee
and that software is perfectly accessible on However, most users wanting a distro they was asked to vote on what direction Debian
the upstream project’s websites. So, instead have control over will be better served by the should go. In simple terms, systemD offered
of downloading a single image with all the likes of Gentoo and Arch. That said, if you more functionality, while Upstart supports
things you need, you download them ever want to know about what goes on Debian flavours with other kernels (the distro
can use the FreeBSD kernel, or GNU’s Hurd).
separately, and this book is a guide for underneath the various distros, LFS is an
One sticking point was the fact that Canonical
combining everything into a working excellent place to start. (which develops Upstart) requires all code
contributors to sign a Contributor Licence
Agreement (CLA) giving Canonical control over
their contribution, including the power to build
non-free software based on it.
In the end, systemD won after the committee
chairman (Bdale Garbee) gave the casting vote.
Following this, Mark Shuttleworth announced
that Ubuntu would drop Upstart (in 14.10)
leaving systemD as the init method on almost
all distributions of Linux.
Not everyone is happy about this. Some
users feel that systemD goes against the Unix
spirit by being monolithic and logging in non-
human-readable binary format. Since it doesn’t
play nicely with other Unix-like systems (such
as the BSDs), anything that relies on systemD’s
It’s the ultimate geek features also won’t work on these systems.
quest, but compiling There is some truth to these complaints, but
a full system takes unless anything changes, it will soon become
time, especially on hard to find a distro that doesn’t use systemD.
older hardware.

www.linuxvoice.com 9
GAMING ON LINUX

GAMING ON LINUX
The tastiest brain candy to relax those tired neurons

VIRTUAL INSANITY
Project Zomboid
Craft your perfect hideout, wait for all this to blow over.

B
rains braaaains
braaaiiins! The game Surviving the zombie
apocalypse has never
devs at The Indie Stone
been so isometric, grrr
have graced us not only with a
arrrgh!
major patch for the hit Project
Zomboid, but have also
introduced tons of new
Liam Dawe is the brains behind
www.gamingonlinux.com, the home features, including the first
of Linux gaming on the interweb. version of their its persistent-
multiplayer. So, now you can go

V
irtual Reality is a hot topic in raiding supermarkets for tins of
gaming right now, and Linux food while your friends on
isn’t being left out in the cold.
another Linux PC stand watch
A company called Oculus VR has
created a headset named the Oculus for zombies outside with a rough), though it is fairly easy When complete, Project
Rift – sounds cool, right? It’s a baseball bat. to get running on a Linux box. Zomboid will have a sandbox
strange-looking device that looks like Anyone is free to run a server The player models have also survival mode, a single-player
it should be in Star Trek. for it, as The Indie Stone is been overhauled, so they have story, split screen co-op and
The good thing about the Oculus
giving away the server tools (be more animations, and the online multiplayer.
Rift is that it has Linux drivers ready,
so it fully supports our platform. warned though that it’s pretty game looks fantastic. http://projectzomboid.com
Alongside the driver support from
Oculus VR we also have Valve; the
company behind Steam. Valve is
pushing out a Virtual Reality API for
game developers, which also
supports Linux.
Strife
The Oculus Rift is a VR device that A ‘second generation’ multiplayer online battle arena from S2 Games.
sits over your eyes strapping you into

S
your game, and that’s where my 2 Games shouldn’t be
problem is. Gaming is supposed to be
a new name to people
a social thing, isn’t it? Being strapped
into some device feels so lonely. Not who have been following
only that, but it’s quite restricting not Linux gaming for a while – the
to be able to see anything else. company has just given out a
The other problem I have is that a whopping load of beta invite for
game is supposed to be a game –
its new multiplayer online battle
why do people now want to emulate
real life to the point of strapping arena (or MOBA for short)
things over their eyes? This is why I’m called Strife. A pirate is just one of the
hoping that it’s a fad, like 3D I was lucky enough to be many characters you can
televisions, 3D movies and the 3D invited and delighted to report choose to play as.
mode on Nintendo’s latest hand-held
that Strife is already fantastic. It
console, which is more of a pain than
anything else. Oculus VR will need to aims to be a more minimalistic
solve issues like eye-strain and MOBA when compared to Strife plays with the MOBA can create your own items to
resolution before it’s taken seriously. games like Dota2. For example, experience by introducing a pet use in-game and gain the
So, to end on a question again for a lot of things are hidden from system. Pets have their own advantage on your opponents.
you lot: will Virtual Reality take-over
view to begin with, although unique abilities, and can be This really is one to look out
our gaming lives, or will it fade away
into oblivion? You decide! you can pin different levelled up using food that you for, especially given S2 Games’
Liam Dawe, gamingonlinux.com information to the screen to acquire after games. There’s history of great Linux support.
suit your playing style. also a crafting system, so you http://strife.com

10 www.linuxvoice.com
GAMING ON LINUX

Planetary Annihilation ALSO RELEASED…
That’s no moon! No wait, it is a moon – and it’s coming this way!

S
o, you have looked up at the moon
and thought to yourself “I wonder
what it would look like if it smashed
into the earth”? Well you don’t need to
wonder about that anymore. The mutant team is
The developers of Planetary Annihilation taking a beating!
have now included the ability to build
massive space drives on moons for you to Mutant Gangland
send them off-orbit and smash into other Micromanegement got you down? Need some
heavenly bodies. flesh pounding against metal? Enter Mutant
They haven’t stopped there either: they Gangland, a very simple-looking turn-based
have also only just included their own strategy game that pits Mutants against
Robots in close-qaurters combat.
version of a Minimap too, which is The game includes a level editor for high
essentially the game running again in a replayability, and also throws in the source
small window on your screen, which uses Planetary Annihilation was funded on code for players to create mods with.
up a lot of memory of course, but it does Kickstarter to the tune of $2,229,344. The team have recently released the ﬁrst
look crazy! alpha version and we will be surprised if this
doesn’t pick up some fans.
This is easily the most intense real-time recommend checking this one out – just http://mutantgangland.com
strategy you can find on Linux, taking don’t blame us= if you get addicted.
inspiration from classics like Total The game is still a little bit on the pricy
Annihilation and Supreme Commander. side right now ($29) but they plan to drop
If you are missing your fix of games like the price once they hit the ‘stable’ version.
those or even Starcraft, we highly www.uberent.com/pa

Plenty of help to
get you started

Starbound The Swapper included for free!

Ever seen a tree with big scary eye-balls You may or may not ﬁnd talking rocks,
Godot Game Engine
for leaves? No? Play this then. it gets a little freaky. Are you an aspiring game developer? Been
looking to make a game, but you don’t know
where to begin? Godot has you covered!
This commercial-grade game-creation kit
has been open-sourced under the MIT licence
to give other engines a run for their money.
It has quite literally everything you need in one
package to begin creating.
www.godotengine.org/wp

So, many, pixels! Starbound is sort of like Only recently released in the latest
Minecraft only in 2D and with far more to Humble Indie Bundle 11, The Swapper
do. This game is an absolute gem, not promises a very atmospheric puzzle-
Easily control
only because one of the developers uses platformer experience. exactly how your
Linux, but because of just how fun it is. When we read-up that everything in the videos look!
You can go from one planet that has big game was made from real-life materials
scary eyeballs for leaves, to a planet that we didn’t realise just how good that could
has pools of lava everywhere and pirates actually look. From an escape-pod that SimpleScreenRecorder
My absolute favourite screen-recorder
chasing you (no really, that happened to looks like a can of beans, to freaky talking software, fully featured and extremely easy to
me once). rocks that look like sponges, the visuals use. I use this software myself to record games
Nothing is more satisfying than taking are completely original. as I have found it to be the only software that
down a massive UFO Boss that warps The game has some very unique can perfectly sync audio and video together.
down little penguins (aww) with bazookas mechanics too: you gain a gun that If you need more to go on, it’s also open-
source and free, so I want to see more of you
(eek!), though it does seem a little barbaric creates clones of yourself, which you can showing us your best play-throughs on the
killing tiny pixellated penguins on a swap control with to solve puzzles. Linux Voice forum!
platform that has a penguin as its mascot! http://store.steampowered.com/ www.maartenbaert.be/simplescreenrecorder
http://playstarbound.com app/231160

www.linuxvoice.com 11
MAIL

YOUR LETTERS
Got something to say? An idea for a new magazine feature?
Or a great discovery? Email us: letters@linuxvoice.com

LINUX VOICE STAR LETTER
GRACE HOPPER computing, such as Niklaus
Wirth, C.A.R. Hoare, Donald
how much faster computers had
become. The picoseconds were
Congratulations on (1981), I learned the basic Knuth and Grace Hopper. a packet of ground black pepper
publishing the first of many “rules” of programming from Years later, I worked as a with the DEC logo and the words
great Linux Voice editions! I a phenomenal designer/ civilian contractor at the “Pico Seconds” printed on it. I
was excited to see a picture programmer, Gordon Vikse, Pentagon. One day while only wish I could have had her
of Rear Admiral Grace who continues to teach walking one of the literally sign mine. Her lesson that it is
Hopper for an upcoming me things to this day. He 17 miles of hallways, I easier to ask forgiveness than
article for next month. In introduced me to the work discovered a display on permission is, in my opinion,
my first job out of college of some of the greats in Grace Hopper, which greatly embodied in the spirit of FOSS
pleased me as it was a richly computing. I’m glad to see that
deserved honor. Shortly Linux Voice is reminding us of the
thereafter, I was even more greatness that has existed, and
pleased to be able to attend continues to exist, in computing.
one of her talks (around Paul Olson, Oklahoma, USA
1990). At the time, she had
been forced into retirement Andrew says: Paul, you’ve made
by the U.S. Navy and was my day. The Grace Hopper tutorial
working as a consultant that we’re running on page 80 isn’t
for Digital Equipment particularly Linuxy, but without Rear
Corporation (DEC). During Admiral Hopper’s work we might
the talk, she told the story of not have Linux at all.The debt that
her nanosecond wires, then we owe the likes of Grace Hopper,
It’s only fair that we acknowledge, in Paul’s words, “the greatness handed out picoseconds to Alan Turing (he’s coming next issue),
that has existed, and continues to exist” in computer science. the audience to demonstrate Donald Knuth et al is enormous.

PAYPONG
I’ve been an enthusiastic reader is concerned. Is there any way
of your work for many years and around this obstacle?
have had a subscription to your Whatever the outcome, good luck
previous magazine, for several with your new venture.
years, bought for me by a family Norman Kearey
member; as a pensioner I need all
the help I can get! Andrew says: We’ve spoken to our
In trying to decide what to do bank about a better online payment
about migrating to your new system, and they aren’t interested
magazine, I discovered that it in helping us until we have at least
is impossible to do so without a year’s accounts under our belt, so,
opening a PayPal account. I distasteful as it is, we’re stuck with
know that this is not a welcome PayPal and its exorbitant fees for now. As much as we dislike it, PayPal is the only way for us to accept
situation, as far as my ‘benefactor’ We’re not happy about it either. payments for magazine subscriptions at the moment.

12 www.linuxvoice.com
MAIL

PUBLISHING THE CODE AHEAD
Thoroughly enjoying your first Big fan of all your work. I’ve been
issue. What caught my eye at listening to the TuxRadar… I mean
first glance was the news that a Linux Voice podcast for a while
new release of Scribus is on the and just got the issue 1 PDF. The
way. Great! I have no doubt that content is great.
this program will be well able You might already be working on
to compete with the extremely these but here’s the two things I’d
expensive equivalents in the love to see:
Windows and the Mac platforms. Have the table of contents and
But there’s a price to pay for cover be made of clickable links
this complexity. In earlier times to those stories. That will avoid
Scribus was easy to use and gave “this story about bitcoin looks
me all the flexibility I needed. Now, interesting, now let me scroll
unfortunately, I can’t perform even through 56 pages to get to it”.
the simplest DTP tasks. Everything An epub version.
seems to work differently and Mark
nothing can be done intuitively.
There’s a complete guide to Graham says: Thanks for the feedback
Scribus in book form but it runs to Mark, we appreciate it. We know that
438 pages! we want to improve the digital offering
Which brings me to my main from PDF-only; at the moment we’re
point: there’s an excellent looking into a HTML 5 container app
Scribus (top) can be
opportunity here for developers can produce good materials for among other solutions, and epub
overkill for most tasks,
to construct a lower-level DTP publication without too much so we’d stick with might be one of those that we settle
program which is usable by effort. But many people need LibreOffice or Inkscape on. There’s a rift between XML and
ordinary human beings rather something more versatile. for simple jobs. HTML advocates at Linux Voice
than high-powered professionals. Maurice George, Ormskirk, Mansions, and this many influence the
Years ago there was ‘Publisher’, an Lancashire formats that we choose. However, it’s
elementary Windows DTP program one of our principles that we should
which appealed to a different user Mike says: I quite agree. The power offer the content in whatever medium
than ‘PageMaker’. So I would urge to change, for example, the spacing the readers want to buy, just as we
open source entrepreneurs to get between individual letters is awesome offer the podcast in MP3, Ogg and
their act together and fill the gap. when you’re doing high-end design Opus files.
Or maybe I’m missing a simpler work, but it’s Scribus and its like are Clickable links in the contents page
alternative in Linux ? Of course massive overkill for most people. though is something that we should
any word processor can design Maybe all it would take is a version of have got right from day one, and if I
basic documents and Inkscape Scribus with features taken out? can remember how to do it we’ll have
it in issue 2.

www.linuxvoice.com 13
MAIL

HEALTHY COMPETITION
Congratulations on an amazing
first issue!
I could not believe when going
through LV01, how much it is
everything I have ever wanted from
a Linux magazine:
Amazing features.
A section dedicated to gaming. In a happy coincidence there’s another
Arch. competition for you on p96.
A challenge after a tutorial.
My name in it :-). Ben says: It’s often easier to learn
Many more! when you have a tangible incentive
I have a print subscription and to do so. That’s why we’re offering
will be with you for the many, many exclusing Linux Voice T-shirts to the
years this magazine will no doubt winners of our coding competitions
be around for. – though of course, if you’re learning
Craig Waites something, you’re already winning.

REDRUM REDRUM REDRUM REDRUM
I understand that you must be net/biamin and browse the code
really busy these days, but you directly at https://gitorious.org/
know what they say: “All work and back-in-a-minute
no play makes Jack a dull boy…” Thanks for providing me with
So I have made a Bash game GNU/Linux knowledge and tips for
called “Back in a minute” that these last 7-8 years, and keep up
may offer some escape. It’s a the good work! Even though my
simple text-based adventure game studies and social life permit little
featuring four playable races, six time for LUGs and other F/OSS
enemies, turn-based fighting, eight related events, listening to your
hidden items and six different podcasts makes up for it and also
scenarios in the 270 sections keeps me up to date.
of the world map. You can also Sigge, Norway
create your own custom ASCII
map for use in the game! Graham says: Thanks Sigge, we’ll
I’m currently doing an MA in show this to Ben as soon as we
political philosophy, so it is nice to release him from the coding tower,
“switch off” every once in a while where he’s been devising this month’s
and play around in Bash a little. competition. And thanks the some
You can find the “Back in a light relief; LV Mansions is starting to
minute” website at http://sigg3. look like the Overlook Hotel.

On second
thoughts, let’s
not play Back In
A Minute. ’Tis a
silly game.

14
MAIL

PIE TIME RANDOM ACTS
First off, congrats on a great Given the revelations that the
premier issue! Ah, most of the old NSA tries to subvert the strength
band is back together again of encryption by weakening
and sounding fine! Now if you algorithms and by subtly altering
just had a physicist on board, the doping of the underlying
and perhaps a female computer silicon, we should be suspicious
language researcher, and… “Linux of the integrity of the random
Voice” is perhaps the best start-up number generators. If the NSA is
investment I have doing such things then it is likely
ever made. that the Chinese are doing the
With all the interest in the same -- the majority of electronics
Raspberry Pi, here is a suggestion are now made in China or Taiwan. outputs when called. This list could The SID chip, as used
that I have been struggling with: How do we know that our also be sent to the NSA. However, on the Commodore
setting up a true real-time version sources of random numbers are any statistical analysis would show 64, is a part-analogue
of Linux on the Pi. I have looked truly random? Can Linux Voice them to be random. Alternatively, sound chip and also
at Open Embedded, Preempt-RT, address this question? Is there a the randomness generator could just an excellent source
of random numbers
Xenomai and more, and they all statistical test that can be applied cycle through non-random numbers
(noise), making it highly
seem promising but I haven’t to /dev/random and /dev/urandom under very specific circumstances.
prized by synth geeks
found a good complete setup yet. to verify that they are continuing The issue did raise its head last and encryption experts
I am trying to sample the Pi’s I/O to provide statistically significant year when an online petition asked alike.
pins deterministically at about sequences of random numbers? Linus to remove the Intel hardware
10~20 kHz to debounce and filter Andrew Shead. random number generator from /dev/
a 1kHz input, so evenly spaced random. Essentially, the issue boils
sampling times without latency is Ben says: You’re right to be concerned down to the fact that Linux generates
important. about random-number generation. It’s a random number itself, then XORs
Congratulations again from the a mathematical weak point in most the number with one generated by the
rural parts of New York State (yes, security systems. hardware random number generator.
there is more to NY than NYC, like One test is to gather output from This method of combination means
500 km of farmland all the way the random generator in Linux (/dev/ that the outputted number will be as
to Canada) and I look forward to random) to a file, then try to zip it. In random as the most random input.
reading you for years to come! theory, it’s impossible for any lossless A compromised hardware generator
Jim Cranston, New York, USA compression to shrink random data, wouldn’t make the system less secure.
so if the zipped file is smaller than the Of course, there’s also nothing to
Graham says: I love the idea of uncompressed file, you have a non- stop a malicious CPU from listening
looking into running real-time stuff random random number generator. for software random number
on the Raspberry Pi. From an audio However, it’s very hard to perform a generators, and manipulating the
perspective, it’s quite easyto build a comprehensive statistical check when output. Ultimately, there’s very
RT kernel for Jack, but I’ll have to look you don’t know what you’re checking little defence against a hardware
into whether it works just as well with for. Imagine, for example, that every manufacturer that wants to spy on
the Pi’s I/O. Stay tuned! CPU is pre-programmed with a list you, except, perhaps, open hardware
of truly random numbers that it design like the work of opencores.org.

TASTY PIE Graham’s Pi Arcade
tutorial on page 74
Could we see more Raspberry Pi
works on other Linux
stuff in the new magazine please
flavours, not just
– in particular, more projects the Raspberry Pi.
would be good.
Matt Osman

Mike says: Of course, but we have
to be careful not to alienate non-Pi
users. Luckily most Pi tutorials apply
The Raspberry Pi is like pulling an idea just as well to generic Linux boxes –
out of your brain and putting it onto a such as the arcade machine tutorial
USB-powered PCB. on page 74. Have fun!

www.linuxvoice.com 15
LUGS ON TOUR

LUGS ON TOUR
OCR Raspberry Jamboree
Linux Voice heads to the land of dark satanic mills
in search of education, innovation and Pi.

I
n the computing world, almost year the two events were run in
everything has an acronym different parts of the Manchester
associated with it, but OCR isn’t Central Convention Complex, but
one we hear very frequently. It this year they combined into the
stands for Oxford, Cambridge and main hall. This was slightly
RSA, though that tells you little. In disturbing given that the Jamboree
fact, it’s an exam board, and charged £20 entrance, yet the EICE
responsible for striking fear into the was free despite giving access to
hearts of 16–18 year-olds across the same area, and the same
Pi demonstrations were
the UK. That should tell you a stands. for teachers, and that is more
provided by Simon
couple of things. Firstly, that the Walters, Ben Nuttall, important in this case.
Raspberry Pi has been Come together Clive Beale and many That’s not to say that the event
phenomenally successful at Annoying though the price other learned and wasn’t good for enthusiasts. The
getting into education: the fact that difference was, it did give the event knowledgeable folk. Raspberry Pi foundation were out in
this is the second year that a major a unified feel. The previous year, force, with Carrie Anne Philbin, Clive
exam board is running the event in there was a Pi event and an Beale, Alex Bradbury and Ben Nutall
Manchester says a lot about the education event. This year, it felt like wandering the floor and meeting
impact of the Pi in schools. there was just one. Alongside a people, though the Uptons didn’t
Secondly, it says that the event is myriad of stands for educational make it as they were in America at
going to have quite an academic technology, you could see teachers the time. The Linux Voice team
feel to it. learning Pi skills, and learning from enjoyed meeting up with fellow
The event is run in partnership the experts. While 2013’s event was Raspberry Pi-ers such as RasPi TV,
As well as the stands,
with the Education Innovation perhaps better for Raspberry Pi Peter Green (of Raspbian fame) and
there was a selection of
Conference and Exhibition. Last enthusiasts, 2014 seemed better talks to learn from. Jack Kelly (organiser of the
Manchester Raspberry Jam,
www.mcrraspjam.org.uk), and
there were plenty more people that
we missed (such as the excellent
folks at MagPi) because we
foolishly went on the Thursday
rather than the Friday.

TELL US ABOUT YOUR LUG!
Chances are that you are already a
member of a Linux User Group (LUG).
LUGs are all over the world and each
one has its own unique selling point,
which draws its members to meet
and discuss their favourite topic. We
want to know more about your LUG
or hackspace, so please write to us at
lugs@linuxvoice.com and we might
send one of our roving reporters to
your next LUG meeting

16 www.linuxvoice.com
LUGS NEWS

South Wales LUG
Mark Einon writes from the land of our fathers.

T
Key signing may seem
he South Wales Linux User (driver’s licence, passport etc) like paranoia to some,
Group (SWLUG) has been in for the keysigning, along with but it’s only sensible
existence for more than 15 your key details. The party will nowadays.
years, in that time supporting local mainly follow the course laid out
users of the Linux operating system in www.cryptnet.net/fdp/crypto/
and other Free Software. keysigning_party/en/keysigning_
In April, SWLUG are adding to party.html.
their usual long-running tradition If you can’t make the afternoon
of well-attended monthly meets in talks in April, stalwart SWLUG
Cardiff and Carmarthen; this time members will still be partaking
organising a series of talks, starting in the usual monthly pub-based
on Saturday 26 April, 2.30–5pm at meetings in both Cardiff (second
FoundersHub (foundershub.co.uk) Tuesday of the month at The City
in the centre of Cardiff. Arms, opposite the Millenium
Expect at least four free and Stadium) and Carmarthen (third
awesome main talks on diverse Tuesday of the month, at Yr Hen you can handle may be found via
Linux topics such as kernel Dderwen on King Street), from the website at www.swlug.org.
internals, hardware accelerated 7.30pm or so where we’re always There you can also find out about
Linux routing, the MIT Athena happy to welcome anyone to our mailing list, IRC channel and
project, and Linux security join whatever their interest or Google+ community where you can
monitoring. There’s also time to experience level. get involved at any time. Look out
fit in a few lightning talks and Lots more details, further for the Eventbrite link to register for
a keysigning party – so don’t updates and ways to join in all the talk attendance and we hope to see
forget some sort of official ID South Wales-based Linuxy action you there!

QCon London
Spend a beautiful spring day in London with some of the world’s smartest coder geeks.

T
his was our first time at
QCon London, and we QCon costs a chunky
can’t believe we’ve missed £2,295 to attend the
an event like this for so long. But conference plus three
days of tutorials.
before you get too excited. It is
expensive to attend. This is one of
those professional events where
you need to surreptitiously place a
cost/benefit analysis chart where
your boss can see it.
The benefits are obvious. Some
of the best developers in the
world, working on some of the
most cutting edge-projects, such
as Spotify and Netflix, all in the
same place and talking about the
challenges they’re facing and how from Game of Life into a talk about
they’re solving them. Each talk we how programming languages are
saw was inventive and engaging. structured, how insane they can be,
But our highlight was Wednesday’s and how he’s invented a own 24th
keynote, presented by Perl maestro century programming language
Damian Conway. Somehow, based on Klingon, complete
he was able to shoehorn John with throat-mangling Klingon
Conway’s (no relation) automata pronunciation.

www.linuxvoice.com 17
LISTEN TO THE PODCAST

WWW.LINUXVOICE.COM

72
REVIEWS INTRO

REVIEWS
The latest software and hardware for your Linux box, reviewed
and rated by the most experienced writers in the business

On test this issue...
20 22

Andrew Gregory
Is at long last planing an expedition to
Dell XPS 13 Retrode
Bletchley Park to visit the old computers. Wireless problems fixed, this Ubuntu- Unlock the fun that’s currently
powered laptop is bringing Linux (and imprisoned in your old games cartridges.
6-hour battery life) to the High Street. Emulation has never been so much fun.

D
on’t it always seem to go, you
don’t know what you’ve got ’til
it’s gone. Yes, it does. 23 24 25
The thing that I had, which I don’t
have any more, is freedom over my
computing environment. Through
necessity I’m spending more and more
time on my new Mac, and the limits are
chafing like a tight sock.
There’s little to no customisation Krita 2.8 PiBorg SolydXK
over the GUI, for instance. Then there’s
Finger painting goes digital: Get into robotics with this Thesis: regular updates.
the lack of a software centre – if you’re
KDE’s image editor gets cheap and cheerful kit Antithesis: rolling releases.
used to installing whatever you want
touchscreen support. powered by the RPi. Synthesis: turn to p25…
through Synaptic or with a simple
apt-get, other operating systems seem
extremely restrictive in comparison.
And the worst thing is that before it lets BOOKS AND GROUP TEST
me update, Apple wants to know my
Trees are good. They provide shelter, for woodland
shoe size, inside leg measurement and
animals, many of which taste good when casseroled.
mother’s maiden name. Not cool at all. They can also be mashed up into paper, which makes
Apple does make fantastic hardware, excellent medium for the written word. This month
and until recently it’s been impossible to we’re mostly reading about the Raspberry Pi, but Ben
find similar quality in a standard laptop. also got his hands on A Computer Called Leo, which
recounts the early adoption of computers by Lyons’
Praise be then, for the Dell XPS 13 – it’s
Tea shops way back in the 1950s, and tells how the
built with Linux in mind in conjunction Brits lost the post-war computing initiative to our
with Ubuntu, and has raised the bar for American colonists despite being jolly good chaps.
your next Linux box. And in the Group Test, it’s text editors.
andrew@linuxvoice.com

www.linuxvoice.com 19
REVIEWS DELL XPS 13 I7-4650

Dell XPS 13 i7-4650
Graham Morrison is happy to discover the wireless problems
that blighted last year’s model have gone.

T
here’s a lot to like about the XPS 13. Thanks to capable of some serious processing and great
DATA machined aluminium and carbon fibre, it’s a graphics performance, and we’d highly recommend
Web
tough, small, powerful, rigid and stylish device going with the latter model for the £100 extra it costs.
www.apt-net.co.uk that’s proved itself in combat. Both last year’s model It’s still significant that this is a Dell machine that
Developer and the new one beneath our collective fingertips comes with Ubuntu 12.04 (LTS) installed, thanks to
Dell feature Intel’s powerful Core i7 architecture, with an what Dell calls Project Sputnik. This noble endeavour
Price incredible 1920x1080 13-inch screen, bright backlit attempts to offer more from Dell than simply buying a
£999 + VAT
keyboard (something essential for nocturnal rambling) laptop with a specification suitable for compiling
and a backpack-friendly form factor. things. The idea started with Stephen O’Grady of
This XPS13 is just 316mm wide, 205mm deep and RedMonk, who suggested there may be a market for
6–18mm high (it’s a wedge), and weighs 1.4kg It’s developers in the emerging cloud markets. The end
slightly lighter than the new 13-inch Apple Macbook result was some custom-developed drivers, mostly for
Pro but the 2cm less depth makes a considerable the Cypress touchpad, and bespoke cloud
difference visually, with no less control from the (still management software, profile management and
larger than average) trackpad. storage that comes with the Developer Edition. These
are great features, but we’re more interested in a
Nice specs major manufacturer offering a Linux laptop along with
The new model has had a specification update, its great recovery tools and support, things which
primarily to accommodate Intel’s new Haswell CPUs don’t usually apply to hardware you buy and then
as well as the inclusion of a touchscreen. With the install Linux on top of. Still, it’s a pity the project hasn’t
CPU architecture update comes Intel’s widely bumped the officially supported version of Ubuntu yet,
respected Intel HD GPU power. There are two variants but that’s probably a business/support issue rather
of the XPS 13, the first with Intel HD Graphics 4400 than anything to do with the way the XPS works with
and an i7 4500U CPU running at 3GHz, and the other version of Ubuntu or any other Linux distro.
second with Intel HD Graphics 5000, i7 4650U at The big problem for us with the previous model was
3.3GHz and a 256GB mSATA SSD, which is the model wireless: it didn’t work. For some reason, the version
we’re looking at here. This is a powerful netbook, we’d been sent didn’t maintain a connection with any

At low-CPU, low screen
brightness and low
keyboard LED settings,
whilst web browsing
and typing, the new XPS
13’s battery lasted an
exceptional six hours.

20 www.linuxvoice.com
DELL XPS 13 I7-4650 REVIEWS

Touchscreen

The most intriguing addition for this model is framework as Android or Ubuntu Mobile,
the inclusion of a touch screen. This is likely swiping down from the screen edges, for
to be because many Windows 8-based example, or touch gestures to rotate and
laptops are now featuring touch capabilities zoom, or the on-screen contention for the
to make some sense of Microsoft’s latest mouse pointer which either represents the
user interface, but it’s a welcome addition for location of the mouse or your touch, the
a Linux laptop, especially when so many touchscreen is an added bonus, rather than a
desktops seem to want to be prodded. reason to buy this laptop in itself.
There are two charge friendly USB 3 ports, a combination Having used a Nexus 10 with a keyboard
mic/headphone jack and a mini-display port. An SD card for some time, we can see the advantages of
slot would have been handy. having both a laptop and touch screen, but
we’re not sure this yet translates into extra
access point for more than a couple of minutes. This usability on the XPS 13. Firstly, the laptop
itself is too light to be prodded much. The
wasn’t an isolated incident either, as there were many
whole unit moves when you touch the
threads and comments online with Ubuntu XPS 13 screen, although thankfully there’s too much
users experiencing the same problems. The problem friction on the screen’s hinge for the angle to
was with the Centrino Advanced-N 6235 wireless change. In Ubuntu 12.04, touching the
chipset and the iwlwifi driver it was using. Despite the screen does help when it comes to moving
Linux emphasis, it seemed a wireless hardware windows out of the way, or selecting text.
We’d say it’s slightly more efficient than with
revision had slipped under the testing dragnet. Dell the touchpad or mouse for specific small Ubuntu 12.04 includes drivers to make
sent out a Killer Wireless-N 1202 as a replacement. jobs. But without the same gesture the touchscreen work out of the box.
But we’re pleased so say the new version doesn’t
suffer connectivity problem at all. Wireless is now
provided by Intel’s 7260 chipset, giving strong, reliable ultra-high resolutions and Linux is that there’s no
’N’ compatible connectivity. Lifting the lid to resume decent system for scaling whilst keeping the fonts at
brought us wireless connectivity in around eight a reasonable size (in the same way Apple does with
seconds, which is only a few moments after you’ve its Retina displays), so until this problem can be
entered your password to unlock the screen. solved, 1980x1080 is the ideal number of pixels for us.
Our system was supplied by Apt-net Ltd, a The only slight hitch was some backlight bleed in the
company that’s going to provide the XPS 13 in the UK lower left of the display. More annoyingly, our model
at no extra charge, free delivery and with a choice of also suffered from a whining sound, emitted most
distributions. To that end, ours came with Fedora 20, loudly when the keyboard backlight was low. The pitch
Ubuntu 13.10, Ubuntu 12.04, OpenSuse and changed depending on the keyboard brightness,
LinuxMint 16 helpfully installed on a 32GB USB stick. hinting at some
Every distribution worked well – much better than
before some of the patches had made it to the kernel.
regulation interference.
Dell’s support thread “Lifting the lid to resume
We’re sure with a little tweaking your favourite distro has lots of people with brought us wireless connectivity
in around eight seconds.”
could feel as well integrated with the hardware as the same issue,
Ubuntu 12.04 does with its custom driver pack. regardless of operating
system, and Dell is
Key reportedly still looking into the issue. It’s worth
We really like the keyboard. We’ve typed tens of checking whether the problem has been resolved
thousands of words on it. Compared to our before you make an order.
benchmark (which is a modern Macbook Pro, sorry!), Overall, this is a fantastic piece of hardware. It’s
it’s got a softer, more cushioned final third of travel, expensive, yes, but it’s designed for people who travel,
which we’d imagine is easier on RSI-battered wrists. want to use Linux and still be as productive as they
The horizontal layout is a little wider than normal, but are with a desktop. It’s also cheaper than the
we soon got used to it, and the LEDs behind the keys equivalent Apple units with a similar form factor –
have variable levels of brightness. The font used on the many of which are used by Free Software geeks at
keys is a little too Sci-Fi for our tastes, but the dimmer conferences. The new XPS 13 is a solid upgrade to a
settings make the keys perfectly legible even in powerful machine with excellent Linux credentials.
complete darkness. The granularity of control of the
screen brightness was perfect, and brightness settings LINUX VOICE VERDICT
were great in a dark room, and sharp in sunlight.
About the most powerful netbook you
The screen itself is gorgeous. As per the original can buy. Light, bright, packed full of
model, we feel that the full HD resolution is a good features and it comes with Linux.
compromise between the amount you can get on the
screen and the clarity of the text. The problem with

www.linuxvoice.com 21
REVIEWS VINTAGE GAME ADAPTER

Retrode
Emulation-nut Mike Saunders is in heaven. And for once,
it has nothing to do with Weißbier…

W
hat a fantastic idea this is. We love
DATA emulators, and spend way too much time
Web
playing classic games from the 80s and
www.retrode.org 90s. But there’s always one problem: the legality of
Developer ROM ﬁles (the ﬁle that contains the data from a
Matthias Hullin read-only memory chip – more or less a clone of a
Price game cartridge). Some people argue that if you
€64.90
already own the physical version of a game, there’s
nothing wrong with playing a ROM ﬁle in an emulator
– but then, where do you get the ROM ﬁle from?
Chances are it has come off a website somewhere,
and generated by someone else, so the legal
questions remain.
The Retrode avoids all of these complications by Plug in your game cart and its contents appear as a ROM
enabling you to play your original Super NES and Sega image on a removable drive – simple as that.
Mega Drive (aka Genesis) cartridges in an emulator on
your PC. And the way it does that it is beautifully emulator such as ZSNES. You’re no longer playing a
simple. It doesn’t require special data transmission random ROM ﬁle from an unknown source, but the
software or custom emulators or anything like that exact code in the physical cartridge that you own.
– it just works out of the box.
On the top of the Retrode are two cartridge slots for Rainbow Road revisited
the aforementioned consoles. Plug in a cartridge, One of the most common annoyances that people
connect the Retrode to your PC via the included USB have with emulators is having to use different
cable, and you’ll see a new removable USB drive controllers to the original machines. You can get
appear. Open this drive and voilà: the contents of the adapters to connect original Super NES and Mega
cartridge are available as a ROM ﬁle (eg for SNES Drive joypads to USB ports, but the Retrode is ahead
games they appear as .sfc ﬁles), ready to play in an of the game here and includes four joypad ports: two
Super NES and two Mega Drive. These appear to the

“It doesn’t require special data transmission
system as standard USB game controllers, so they
will work with any emulator.
software or custom emulators – it just works.” And it gets better: if the game has battery-backup
save states, in many cases you can access them too.
We plugged in our copy of Super Mario Kart that we
bought in 1992, and a .srm ﬁle containing our lap time
records appeared on the drive, which loaded
Shiny and black, the Retrode seamlessly into ZSNES. If you have some saved
reminds us very much of the
games that mean the world to you, and you’re worried
Sega Master System II.
about the in-cart batteries dying, you need this. Now.
The Retrode worked with all the Mega Drive (5) and
SNES (8) cartridges we tested, although there are
compatibility notes on the website, so it’s worth
checking those before buying the device. You can
even get adapters to play Nintendo 64, Game Boy and
Master System games. We’re beaming with delight at
the prospect of getting our old Wave Race 64 records
off the cartridge…

LINUX VOICE VERDICT
A brilliant idea, executed well. Not
cheap for casual gamers, but for
hard-core emulation fans it’s bliss.

22 www.linuxvoice.com
KRITA REVIEWS

Krita 2.8
Ben Everard decamps to the South of France, pours himself a coffee,
cuts off his ear and searches for his artistic side.

I
mage editing software comes in many different
forms. The majority we come across, are for
touching up photographs. Krita, though, is
different. It’s designed for digital drawing, and creating
new images rather than touching up existing ones.
Think of it as digital painting software and you’ll be
pretty close. It does have some filters that could be
used to touch up photos, but you’d almost always be
better off with other software for this.
Digital drawing covers quite a wide range of tasks,
and Krita is surprisingly capable of meeting most
challenges. It’s simple and intuitive enough for most
beginners to get started with quickly. The range of
brush presets has been improved in 2.8, and using
just these and a bit of clicking, most people can start
to create something loosely resembling art. If you
possess some basic artistic talents, you should be It’s a sunset over an ocean, in case you were wondering.
able to make something looking good quite quickly.
Yet despite how easy it is to get started, Krita is still Intel, presumably as a way to show off laptops that
complex and powerful enough to suit the needs of can convert into tablets (see the demo video at www. DATA
many professional digital artists. The dockers youtube.com/watch?v=qiSGuCzRZFk). This looks Web
interfaces make it easy to show or hide functionality pretty, but it’s almost useless unless you own a very www.krita.org
so you have access to the tools you need, but don’t specific type of device, especially as there’s no Developer
overcrowd the window. For serious users, various Android support. Krita Foundation
Price
levels of commercial support are available through There is some good news for Linux users. The
Free under GPL or from
www.kritastudio.com. wrap-around mode makes it much easier to create €225 per person per year
tiling images, which is great if you’re working on game
Free software on Windows art. OpenGL support has also been improved, so
2.8 is an important release for the project and will some of the rendering can now be offloaded to free up
probably see a large uptake in users for two reasons: the CPU. The developers claim that support for
it’s the first stable version for Windows, and it’s graphics tablets has been improved, though we don’t
been greenlit by the community to come to Steam have a device to test this on. Along with the usual
(www.steamcommunity.com/sharedfiles/ bugfixes, this adds up to a useful, though not overly
filedetails/?id=225403385). While this is exciting exciting release.
news for the project, neither of these things really We can forgive Krita 2.8
affects how the software performs for us Linux users.
But still, welcome to the party, everyone else!
for being focused on
Windows. After all, it’s the
“Krita is powerful enough
Krita now comes with Krita sketch. This is the a first stable Windows to suit the needs of many
new user interface that’s been designed for
touchscreens. It was developed in partnership with
version. If this makes it
easier for KO GmbH (the
professional digital artists.”
company that supports
development of Krita) to fund development, then we
all win. There’s nothing wrong with version 2.8, but,
unless you need wrap-around mode, or happen to
own a laptop that transforms into a tablet, there’s little
reason to rush out to download the latest version.

LINUX VOICE VERDICT
A solid release for Linux users,
and an exciting release for
Windows users.
Krita Sketch is useful for posing with transformable
touchscreen laptops, but not much else.

www.linuxvoice.com 23
REVIEWS ROBOTICS KIT

PiBorg PiCy
Ben Everard loses hours of his life to this little kit that
sets your Raspberry Pi free to roam around the kitchen.

T
he Raspberry Pi is a great base for robotics
DATA projects of all shapes and sizes, and the PiCy
Web
is about as small as they come. It’s just a
www.piborg.org Raspberry Pi case with a pair of motors and wheels.
Developer Assembling the kit requires a little soldering, though
PiBorg none of it is difficult or fiddly (the kit is also available
Price pre-soldered for an extra £7). Everything else can be
£29.99 (not including
Raspberry Pi)
assembled with no tools at all. The case snaps over
the Pi, the motors and battery case are glued on, and
the wheels are just pushed into place. It took us about
30 minutes to build ours, and that included time to
take step-by-step photos.
The only electronics are a small circuit board to
power the motors. This board (called a PicoBorg) is
just a group of Field Effect Transistors (FETs) that are
used to control higher-power devices such as motors. WThe PicoBorg (the electronics at the heart of the kit) is
Once assembled, controlling it is just a matter of available by itself for £6.99 including UK shipping.
using the GPIO pins. There’s example code on the
PiBorg website to do this with Python, though it could The essence of robotics is compromise, and in
be done in other languages if you prefer. Getting this order to make it easy to get started, the kit sacrifices
running was as easy as assembling it. Most other some things. The glued-together frame doesn’t feel
motor control boards for the Pi use special libraries to particularly strong, so it’s unlikely to cope well with
control the hardware. The fact that this works on pure rough handling. That said, the first thing to break will
GPIO output makes it a great first kit for anyone who almost certainly be the double-sided tape, which
wants to learn more about controlling things with the would be trivial to repair.
Pi. However, this does give you less control over the
motors – you can only turn each one on or off, so My First Robot
there’s no speed control and no reverse. The two video connectors on the Pi are inaccessible
when it’s strapped into the PiCy, so you couldn’t use

“Considering how easy it is to program, this as a base for anything with a HDMI screen, but

the PiCy is a great introduction to robotics.”
then it’s not likely to be big enough for that anyway.
To get up and running, you’ll need the PiCy kit, a
Raspberry Pi and the usual paraphernalia (SD card,
power supply, etc). The main base for the chassis is a
ModMyPi case, which is excellent at protecting the Pi,
but doesn’t make a very expandable basis on which to
build. There aren’t any holes or anything else to mount
additional hardware on. The best bet for expanding it is
either gluing parts on or drilling into the case. On the
plus side, there are two unused protected GPIOs on the
PicoBorg (including one with PWM) to add more
motors or other peripherals to your robot. At this price,
and considering how easy it is to assemble and
program, the PiCy is a great introduction to robotics,
and the parts it’s made from can easily be recycled into
to more advanced projects as your skills develop.

LINUX VOICE VERDICT
Possibly the easiest way that we’ve
seen to to build a robot based on the
Raspberry Pi.
Though not strictly necessary, a portable USB power supply will let you run your creation
untethered, and a Wi-Fi dongle will enable you to communicate with it once it’s free.

24 www.linuxvoice.com
DISTRIBUTION REVIEWS

SolydXK 201401
Does the world really need yet another Debian-based distro?
Well, the answer is yes, as Mike Saunders discovers.

S
olydXK is an unassuming distro that could very
easily have missed your radar. After all, how
many other desktop-oriented Debian spin-offs
are doing the rounds? We’ve lost count now. But after
two readers mentioned SolydXK in last issue’s letters
page, we had to take it for a spin. And we’re glad we
did, because its release model could become the
norm for desktop distros in the future.
Right now, there are two main ways that distro
makers approach releases: some, like Ubuntu and
Fedora, create one or two big releases each year.
Everyone waits patiently for several months and then
does the big upgrade to get all the hottest new
software. It works fairly well, but sometimes it’s a drag
having to wait. Then there’s the rolling model, as used
prominently by Gentoo and Arch, where you get new
software as soon as it’s released by the original
developers. This lets you live on the bleeding edge, but
things can occasionally break due to a lack of testing
and integration.
SolydXK is a half-way house; you only have to install
it once, and then every three months you’ll receive Some people will like the distro’s use of a plain KDE setup, but we’d like to see a bit more
Update Packs to get the latest software. So there are individuality shine through – or you could follow page 84’s tutorial and tweak it yourself.
no fanfare-surrounded major releases where everyone
rushes to upgrade – you just get the newest Mint’s attractive Software Manager is included, and
programs in well-tested bundles. This is a great the installer is also based on Mint’s. DATA
approach, and hope to see it adopted by more There are a few rough edges: the presentation and Web
desktop Linux distributions. theming isn’t very slick, and some work could be done www.solydxk.com
to tidy up the menus (having both Package Manager Developer
What’s in the box? and Package Installer in the System menu could The SolydXK team
Price
Two versions are available: KDE and Xfce (we tested confuse new users, for instance). But the SolydXK
Free (various open
the former here). In use it’s a fairly vanilla Debian team has demonstrated real commitment to the source licences)
testing-based distro with a stock KDE 4.12 installation, project, with installation videos on the website, a
supported by LibreOffice 4.1, Firefox 26 and various growing community, and annual reports explaining
other desktop apps. VLC is included together with a how things are
progressing.
“The SolydXK team
bunch of media codecs, so the distro can handle most
formats from the get-go. Along with Synaptic, Linux Time will tell if the
Upgrade Packs work as
intended and the goal of has demonstrated real
“you don’t have to reinstall, commitment to the project.”
ever” can be achieved. But
it’s certainly a distribution
to keep an eye on, and if it gathers enough interest it
could make some of the others (with their traditional
timed-interval release cycles) start to look rather
old-hat.

LINUX VOICE VERDICT
A promising distro with a fresh
approach to updates – it just needs
more personality of its own.
SolydXK’s Mint-based installer is quick, easy to use and
versatile enough for power users.

www.linuxvoice.com 25
REVIEWS BOOKS

Adventures in Raspberry Pi
& Raspberry Pi USer Guide
Andrew Gregory spends some rainy days with the world’s favourite Linux machine.

T
he Raspberry Pi came about installing Raspbian with Noobs, an
because Eben Upton, the PiFather, introduction to the command line, the
decided that something needed to Scratch programming language, drawing
be done to improve the quality of students with a Python turtle (just like we’re doing this
applying to study on his university computer issue with our Python tutorial on p96). The
science courses. So far, so sensible, and you final project is building a jukebox with the Pi,
can read more about the effect that the using a speaker, a breadboard an LCD
raspberry Pi is having on education in our display and the Pi’s GPIO pins. This is the
interview with the Pi Foundation’s education sort of thing that a supportive parent would
team on page 46. But the Pi has also found be likely to find were they to simply Google
an audience among the massed legions of for Raspberry Pi projects, and for most
home tinkerers, shed solderers, robot people it’s just too challenging. Adventures
builders, beer brewers and people who in Raspberry Pi slowly builds up the difficulty,
generally have an interest in home hackery. constantly challenging the newcomer to
The two books we’re looking at here have learn more and improve on their skills, and
these two readerships in mind. Adventures that’s what makes it such an excellent book
in Raspberry Pi, by Carrie Anne Philbin, is for teachers, kids, parents or just non-
aimed squarely at children, teachers and technical humans who want to learn a bit. If we had to sum this book up in a word, that
parents looking for a way into computer word would be: accessible.
science. Raspberry Pi User Guide, with its Raspberry Pi User Guide
oh-so-serious graph paper on the cover (a In contrast, Raspberry Pi User guide is very reference book. There’s (luxury!) a
brilliant idea) is targeted at the older hacker, much preaching to the converted. It’s a geek nice index, and its pages speak of
at adults who have some experience of fest, and almost seems designed to deter authority. Even though it’s not
programming, and who want to transfer casual readers. There’s a discussion on the especially weighty at 300 pages
their existing knowledge to this relatively merits of x86 vs ARM chips for instance, – OK, so it’s not light reading, but
new device. and sections on relatively advanced and computer tomes often come in at
It’s not surprising then that Adventures is stuff like network configuration and HDMI around the 800 mark – it feels like
the more accessible of the two. The book is display modes. a definitive, official work. There’s a
divided into nine adventures, beginning with Whereas Adventures presents a smooth confidence to the writing that you
learning curve, User Guide feels like it’s had can feel as a reader. This feels like a
facts packed into it rather than projects, definitive work.
diminishing its usefulness as a learning tool. Which of these books work for
The chapter on Scratch, for example, the you depends on you. We’d
programming language aimed at kids, recommend them both in a
comes after the chapter on using the Pi as a heartbeat. You won’t like both of
web server. This doesn’t make sense to us. these, but you will definitely like one
While not that great as a structured or the other, depending on where
programme of learning, User Guide is a great you are in your Linux journey.

LINUX VOICE VERDICT
ADVENTURES IN
RASPBERRY PI RASPBERRY PI USER GUIDE
Author Carrie Anne Philbin Authors Gareth Halfacree & Eben Upton
Publisher Wiley Publisher Wiley
ISBN 978-1-118-75125-1 ISBN 978-1-118-79548-4
Price £14.99/US $24.99/CAN $29.99 Price £17.99/US $19.99/CAN $23.99
Brilliantly thought out, this is the perfect Contains many facts, all of them true. The
guide to catalyse computing curiosity. definitive reference guide.
If we had to sum this book up in a word, that
word would be: authoritative.

26 www.linuxvoice.com
REVIEWS BOOKS

A Computer Called LEO ALSO RELEASED…
Ben Everard discovers that tea shops and computers go together.

T
he story of how Silicon Valley grew
to dominate the computing world
has been told many times, but it’s
not the only tale of how computers
developed. While IBM were still building
adding machines, a British company
famed for its teashops built its own It’s just like Downton Situational
computer and ran the world’s first office Abbey, just with awareness is
computing jobs. They ran payroll, computers and forty the key phrase
management accounting jobs and others years into the future. for network
long before anybody else realised such analysis
things were possible. just don’t expect a tech-heavy geek fest. Network Security Through Data
In A Computer Called Leo, Brenda It’s perfect for reading over a cream tea on Analysis
Maddox charts the history of this very a sunny afternoon with the tune of Rule This book looks like the networking security
British company and how it started the Britannia gently wafting through the air. equivalent to Crystal Maze. It gives you the
tools to snoop on your own network trafﬁc in
office computer revolution. It’s not a
an attempt to head off the bad guys before
technical exploration of how they worked, LINUX VOICE VERDICT they even know they’ve been found.
but a gentle history of what ultimately Author Brenda Maddox
became a side-note in technology. Publisher Harper Collins
It is, perhaps, an important story of how ISBN 978-1-84115-186-1
Price £11.99
plucky British boffins created some of the
Computers, tea and cakes. Chuck in a pint
best technology in the world, but of real ale and you’ve got the perfect way to
ultimately failed in the face of international spend an afternoon.
competition. You can read this as a
cautionary tale or an entertaining story, Tin cans and
a piece of
string? You
were lucky. All
Arduino for dummies we had were
yoghurt pots.
Ben Everard ignores this book’s cover, then enjoys the contents.
Remote Pairing

T
he Arduino is probably the easiest Feeling lonely? Paired programming is the
latest thing to help isolated programmers
way to get started in interactive develop more of a social life, whilst learning to
electronics. That said, anything interact with real human beings. Actually, it’s
that involves programming or electronics not. It’s a cool new methodology that’s proving
is guaranteed to scare some people. two heads are better than one.
Anything that involves both programming
and electronics (as the Arduino does) is
going to scare quite a few people.
This reviewer has always steered clear
of ‘For Dummies’ titles because they seem
to confuse not knowing about a subject
with stupidity. This book is clearly for
people who don’t know about the Arduino,
dummy or not. A dummy who happened
to know about the Arduino wouldn’t have Python and Pi:
much use for the book and is probably a Ben isn’t a dummy, but he enjoyed this book. a match made
very dangerous person to have around in heaven.
(never let them plug anything into your LINUX VOICE VERDICT Learning Python with Raspberry Pi
power sockets). Author John Nussy This book looks so wonderful, so learned and
Title aside, this book is a gentle intro to Publisher John Wiley and sons so entertaining we’ve already enlisted the help
ISBN 978-1-118-44637-9 of top book reviewer, Brander Eve, to take a
the Arduino starting from the assumption
Price £16.99 look at this title for us. Early reports indicate
that the reader knows nothing about
One of the gentlest introductions to the it’s everything we hoped it would be, but we’ll
electronics or programming and building Arduino, if you can stomach the title. wait on Brander’s ﬁnal verdict next month.
up from there. Despite this, it covers a
wide range of hardware and projects.

www.linuxvoice.com 27
GROUP TEST ADVANCED TEXT EDITORS

ADVANCED
TEXT EDITORS
GROUP TEST
Mayank Sharma tests ﬁve supercharged text editors that
can crunch more than just words.

On Test Advanced Text
Gedit
URL http://projects.
Editors
gnome.org/gedit/ The right editor can be passport to a better Linux.

I
Version 3.10
Licence GPL f you’ve been using Linux long, Some simple text editors even
Is Gnome’s default text you know that whether you exceed their design goals thanks to
editor up to the challenge? want to edit an app’s plugins that infuse them with
conﬁguration ﬁle, hack together a capabilities to rival text-centric apps

Kate shell script, or write/review bits of
code, the likes of LibreOfﬁce just
from other genres. They can take
on the duties of a source code
URL www.kate-editor.org won’t cut it. Although the words editor and even an Integrated
Version 3.11 mean almost the same thing, you Development Environment.
Licence LGPL/GPL don’t need a word processor for Two of most popular and
Will Kate challenge fate?
these tasks; you need a text editor. powerful plain text editors are
In this group test we’ll be looking Emacs and Vim. However, we didn’t
at ﬁve humble text editors that are include them in this group test for a
more than capable of heavy-lifting couple of reasons. Firstly, if you are
Sublime texting duties. They can highlight using either, congratulations: you
syntax and auto-indent code just as don’t need to switch. Secondly, both
URL www.sublimetext.
com effortlessly as they can spellcheck of these have a steep learning
Version 2.0.2 documents. You can use them to curve, especially to the GUI-oriented
Licence Proprietary record macros and manage code desktop generation who have
Proprietary software in snippets just as easily as you can access to alternatives that are
the land of free with the copy/paste plain text. much more inviting.
heart of gold.

UltraEdit “Some simple text editors even exceed
URL www.ultraedit.com
Version 4.1.0.4
their design goals thanks to plugins.”
Licence Proprietary
Does it do enough to
justify its price?
THE CRUCIAL CRITERIA
All the tools, except Gedit and jEdit, of the desktop environment they are
were installed on Fedora and Ubuntu via running on. That not only rules it out as
their recommended installation method. an evaluation criterion, it also means
jEdit The former already shipped with the
default Gnome desktop and the latter
that you are no longer bound by the
tools that ship with your favourite
URL www.jedit.org stubbornly refused to install on Fedora. desktop environment.
Version 5.1.0 Since these are relatively simple apps, In addition to their geekier
Licence GPL they have no esoteric dependencies, functionality, we also tested all our
Will the Java-based the only exception being jEdit, which candidates for general-purpose text
editor spoil the party requires Oracle Java. editing. However, they are not designed
for the rest? Thanks to the continued efforts of to mimic all the functionality of a
both Gnome and KDE, all editors look modern-day word processor and weren’t
great and function properly irrespective evaluated as such.

28 www.linuxvoice.com
ADVANCED TEXT EDITORS GROUP TEST

Programming Keyboard
language support control
They’re called code editors for a reason. Flex those ﬁngers!

U
sers of an advanced text editor expect
to control and operate it exclusively
via the keyboard. Furthermore, some
apps even allow their users to further
customise the key bindings for the shortcuts.
You can easily work with Gedit using its
extensive keyboard shortcut keys. There are
keys for working with and editing ﬁles as well
as invoke tools for common tasks such as
spellchecking a document. You can access a
list of default shortcut keys from within the
app, but there’s no graphical way to customise
them. Similarly, to customise the keybindings
in Sublime, you need to make modiﬁcations in
its XML keymap ﬁles. Sublime has been
Kate can double up as a very versatile and capable integrated development editor. criticised for its lack of a graphical interface to
deﬁne keyboard shortcuts, but long-term users

U
ltraEdit does syntax highlighting, navigating long code ﬁles and lets you have defended the current ﬁle-based
can fold code and has project jump between different parts of the ﬁle. mechanism, which gives them more control.
management capabilities. There’s One of the best features of Sublime is UltraEdit is proud of its “everything is
also a function list, which is supposed to its ability to run code for certain languages customisable” motto, which it extend to
list all the functions in the source ﬁle, but it like C++, Python, Ruby, etc from within the keyboard shortcuts. You can deﬁne custom
didn’t work for any of our test code ﬁles. editor itself, assuming of course you have hotkeys for navigating the menus and also
UltraEdit also supports HTML5, and has a the compiler and other build system tools deﬁne your own multi-key key-mappings for
HTML toolbar with which you can add installed on your computer. This helps accessing its plethora of functions.
commonly-used HTML tags. save time and eliminates the need to In addition to its fully customisable keyboard
Even Gnome’s default text editor, Gedit, switch out to the command line. shortcuts, jEdit also has pre-deﬁned keymaps
has several code-oriented features such You can also enable the build system in for Emacs. Kate is equally impressive in this
as bracket matching, automatic Kate with plugins. Furthermore, you can respect. It has an easily accessible window to
indentation, and will also highlight syntax add a simple front-end to the GDB customise the key bindings. You can change
for various programming languages debugger. Kate will work with Git, the default keys, as well as deﬁne alternate
including C, C++, Java, HTML, XML, Subversion and Mercurial version control ones. Furthermore, Kate also has a Vi mode
Python, Perl, and many others. systems, and also provides some which will let users operate Kate using Vi keys.
If you’re looking for more programming functionality for project management.
assistance, look at Sublime and Kate. It does all this in addition to highlighting
Sublime supports several programming syntax for over 180 languages, along with
languages and (as well as the popular other assistance like bracket matching,
ones) is able to highlight syntax for C#, D, auto-completion and auto-indentation. It
Dylan, Erlang, Groovy, Haskell, Lisp, Lua, also supports code folding and can even
MATLAB, OCaml, R, and even SQL. If that collapse functions within a program.
isn’t enough for you, you can download The only disappointment is jEdit, which
add-ons to support even more languages. bills itself as a programmer’s text editor,
Furthermore, its syntax highlighting but it struggled with other basic functions
ability offers several customisable such as code folding and wouldn’t even Both UltraEdit and Kate have options to print a
options. The app will also match braces, suggest or complete functions. reference guide for all their keyboard shortcuts.
to ensure they are all properly rounded off,
and the auto-complete function in Sublime VERDICT VERDICT
works with variables created by the user. Gedit Gedit
Kate Kate
Just like Komodo IDE, sublime also Sublime Sublime
UltraEdit UltraEdit
displays a scrollable preview of the full jEdit jEdit
source code, which is really handy for

www.linuxvoice.com 29
GROUP TEST ADVANCED TEXT EDITORS

Snippets and Ease of use
macros Inviting or intimidating?

U
nlike a bare-bones text editor, the Although at ﬁrst glance most apps in
Because time is money. text editors in this feature are this group test have a very similar layout,
brimming with features to upon closer inspection, you’ll notice
Macros help you cut down the time spent on accommodate a wide range of users -- several usability differences. We have a
editing and organising data by automating from document writers to programmers. weak spot for apps that expose their
repetitive steps, while Snippets of code Instead of stripping features from the functionality and features by making
extend a similar functionality to programmers apps, their developers are looking for judicious use of the user interface, instead
by creating reusable chunks of source code. avenues to add more functionality. of just overwhelming the user.
Both have the ability to save you time.
The vanilla Gedit installation doesn’t have
either of these functionalities, but you can Gedit
enable them via separate plugins. While the Gedit wears a very vanilla look. It has an a tool enabled by a plugin. The app will
Snippets plugin ships with Gedit, you’ll have to easy interface with minimal menus and detect when an open ﬁle is modiﬁed by
manually download and install the macro buttons. This is a two-edged sword another application and offers to reload
plugin (it’s called gedit-macropy and is though, as some users might fail to realise that ﬁle.
hosted on GitHub) before you can enable it its true potential. The UI has been given a major overhaul
from within Gedit. The app can open multiple ﬁles in tabs in the latest version of the app yet to make
Kate takes the same plugins route to that can be rearranged and moved its way into Gnome. However it isn’t yet
enable the snippets feature. Once added, the between windows. Users can optionally stable, and while it maintains all features,
plugin also adds a repository of snippets for enable panels on the side and bottom for several plugins that interact with the
PHP, Bash and Java. You can display the list displaying a ﬁle browser and the output of menu will need to be updated.
of snippets in the sidebar for easier access.
Right-click on a snippet to edit its contents as
well as its shortcut key combination.
However, very surprisingly, it doesn’t support
macros – despite repeated hails from users
There’s a ﬁne balance
since 2002!
between stufﬁng an app with
jEdit too has a plugin for enabling snippets. features and exposing all
But it can record macros from user actions of them to the user – Gedit
and you can also write them in the BeanShell keeps most of its features
scripting language (BeanShell supports hidden.
scripted objects as simple method closures
like those in Perl and JavaScript). jEdit also
has a plugin that will download several Kate
macros from jEdit’s website. Although a major part of its user interface with multiple ﬁles at the same time. But
Sublime ships with inbuilt ability to create resembles Gedit, Kate tucks in tabs at unlike the traditional horizontal tab
both snippets and macros, and ships with either side and its menus are much fuller. switching bar in most app, Kate has tabs
several snippets of frequently used functions The app is approachable and invites users on either side of the screen. The left
for most popular programming languages. to explore other features. sidebar will display an index of open ﬁles.
Snippets in UltraEdit are called Smart Kate can transparently open and save Programmers who need to see different
Templates and just like with Sublime you can ﬁles over all protocols supported by KDE’s parts of the same ﬁle at the same time will
insert them based upon the kind of source ﬁle KIO including HTTP, FTP, SSH, SMB and also appreciate its ability to split the
you’re editing. To complement the Macro WebDAV. You can use the app to work interface horizontally as well as vertically.
recording function, UltraEdit also has an
integrated javascript-based scripting
language to automate tasks. You can also
download user-submitted macros and scripts
from the editor’s website.

VERDICT
Gedit
Kate
Sublime KDE’s philosophy of exposing
UltraEdit functionality to the user
jEdit
applies to Kate, and works
well in this context.

30 www.linuxvoice.com
ADVANCED TEXT EDITORS GROUP TEST

Sublime Text
Sublime lets you view up to four ﬁles at
the same time in various arrangements.
ﬁles. The app ships with several snippets
for popular functions in several Availability and
support
There’s also a full-screen distraction free programming languages, which makes it
mode that just displays the ﬁle and the very usable for developers. Another neat
menu, for when you’re in the zone. editing feature, whether you are working
The editor also has a minimap on the with text documents or code, is the ability
right, which is useful for navigating long to swap and shuffle selections.
Where do you look for help?
There are several similarities between Gedit
and Kate. Both apps take advantage of their
respective parent project, Gnome and KDE,
and are bundled with several mainstream
distros. Yet both projects are cross-platform
and have Windows and Mac OS X ports as
If you don’t like Sublime’s well as native Linux versions.
default ‘Charcoal’ appearance Gedit is hosted on Gnome’s web
you can choose one of the 22 infrastructure and has a brief user guide,
other themes it includes. information about the various plugins, and the
usual channels of getting in touch including a
mailing list and IRC channel. You’ll also ﬁnd
UltraEdit usage information on the websites of other
UltraEdit’s interface is loaded with several ﬁngertips. You can also access remote Gnome-based distros such as Ubuntu.
toolbars at the top and bottom of the ﬁles via FTP and SFTP. Advanced features Similarly, Kate gets the beneﬁt of KDE’s
interface. Along with the tabs to switch such as recording a macro and comparing resources and hosts detailed user information
between documents, panes on either side ﬁles are also easily accessible. as well as a mailing list and IRC channel. You
and the gutter area, these leave little room Using the app’s Preferences window can access their respective user guides
for the editor window. you can tweak various aspects of the app, offline from within the app as well.
Web developers working with HTML including the colour scheme and other UltraEdit is also available for Windows and
ﬁles have lots of assistance at their features like syntax highlighting. Mac OS X besides Linux, and has detailed
user guides on getting started, though there’s
none included within the app. To assist users,
UltraEdit hosts a database of frequently
asked questions, a bunch of power tips that
have detailed information about several
UltraEdit’s UI is highly
speciﬁc features, and users can engage with
conﬁgurable – you can
customise the layout of one another other on forum boards.
toolbars and menus just as Additionally, paid users can also seek support
easily as you can change from the developers via email.
many other aspects. Sublime supports the same number of
platforms, however you don’t need to buy a
separate licence for each platform. The
jEdit developer keeps users abreast with ongoing
In terms of usability, one of the ﬁrst inbuilt help, which will help ease the development via a blog and also participates
red-flags was jEdit’s inability to install on learning curve. actively in the hosted forums. The highlight of
RPM-based distros. Navigating the editor jEdit highlights the current line you are the project’s support infrastructure is the
takes some getting used to, since its on and enables you to split windows in freely available detailed tutorial and video
menus aren’t in the same order as in other multiple viewing modes. You can easily course. Sublime is lovely.
popular apps and some have names that install and manage plugins from within the Because it’s written in Java, jEdit is
won’t be familiar to the average desktop app, and in addition to full macros, jEdit available on several platforms. On its website
user. However, the app include detailed also lets you record quick temporary ones. you’ll ﬁnd a detailed user guide and links to
documentation of some plugins. However,
there are no avenues for users to engage with
other users or the developer.

VERDICT
Gedit
Kate
Thanks to its Java Sublime
UltraEdit
underpinnings, jEdit doesn’t jEdit
really feel at home on any
desktop environment.

www.linuxvoice.com 31
GROUP TEST ADVANCED TEXT EDITORS

Add-on and plugins
To flesh out new features.

D
ifferent users have different all the ﬁles in the same tab order as you
requirements, and a single saved them.
lightweight app can only do as Similarly, you can extend Kate by
much. This is where plugins come into adding plugins using its built-in plugin
the picture. The apps rely on these manager. In addition to the impressive
small pluggable widgets to extend their projects plugins, some others that will
feature set and be of use to even more be of use to developers include an
number of users. embedded terminal, ability to compile You can run any external command or shell script in Gedit
The one exception is UltraEdit. The and debug code and execute SQL by deﬁning it as an external tool.
app has no third-party plugins, but its queries on databases.
developers do point out that third-party categories such as File Management,
tools such as HtmlTidy are already Sublime plugins Version Control, Text, etc. You’ll ﬁnd lots
installed with UltraEdit. Plugins for Sublime are written in of plugins housed under each category.
Gedit ships with a number of plugins Python, and the text editor includes a Some of the best plugins are the
installed, and you can download more tool called Package Control, which is a Android plugin, which provides utilities
with the gedit-plugins package. The little bit like apt-get in that it enables the to work on Android projects; the
project’s website also points to several user to ﬁnd, install, upgrade and remove TomcatSwitch plugin, using which you
third-party plugins based on their plugin packages. With plugins, you can can create and control an external
compatibility with the Gedit versions. bring the Git version control to Sublime, Jakarta Tomcat server process; and the
Three useful plugins for as well as the JSLint tool to improve Vimulator plugin, for Vi-like capabilities.
programmers are Code Comment, JavaScript. The Sublime Linter plugin is You can install these plugins using
Terminal Plugin, which adds a terminal a must have for coders and will point jEdit’s using its plugin manager.
in the bottom panel, and the Session out any errors in your code.
Saver. The Session Saver is really useful jEdit boasts the most impressive VERDICT
when you’re working on a project with plugin infrastructure. The app has over Gedit
Kate
multiple ﬁles. You can open all the ﬁles 200 plugins, which can be browsed in Sublime
UltraEdit
in tabs, save your session and when the dedicated site of their own. The jEdit
you restore it with a single click it’ll open website lists plugins under various

Plain ol’ text editing
How good are they as just simple editors ?

D
espite all their powerful highlighted text. It’s also got a line
extra-curricular activities that modiﬁcation system which visually
might even displace full-blown alerts users of lines which have
apps across several genres, there will modiﬁed and unsaved changes in a ﬁle.
be times when you just need to use In addition, it enables users to set
these text editing behemoths to read, bookmarks within a ﬁle to ease
write, or edit plain and simple text. navigation of lengthy documents.
While you can use all of them to enter Sublime has a wide selection of Sublime
text, we are evaluating them for access editing commands, such as indenting Text offers ﬁles via FTP. One unique feature of jEdit
to common text-editing conveniences. text and formatting paragraphs. Its some is its support for an unlimited number
Gedit which is Gnome’s default text auto-save feature helps prevent users unique of clipboard which it calls registers. You
editor, supports an undo and redo from losing their work. Advanced users features to can copy snippets of text to these
manipulate
mechanism as well as search and will appreciate the regex-based registers which are available across
text.
replace. It can spellcheck documents in recursive ﬁnd and replace feature, as editing sessions.
multiple languages and can also well as the ability to select multiple
access and edit remote ﬁles using non-contiguous spans of text and act VERDICT
Gnome GVFS libraries. on them collectively. Gedit
Kate
You can spellcheck documents with UltraEdit also enables the use of Sublime
Kate as well, which also lets you regular expressions for its search and UltraEdit
jEdit
perform a Google search on any replace feature and can edit remote

32 www.linuxvoice.com
ADVANCED TEXT EDITORS GROUP TEST

OUR VERDICT
Advanced text editors
A
ll the editors in this feature outscores Gnome’s default editor
are good enough to replace even after taking their respective
your existing text editor for plugin systems into consideration. Despite being a KDE app, Kate looks good across many desktops.
editing text ﬁles and tweaking Both Sublime and Kate are
conﬁguration ﬁles. In fact, chances
are they’ll even double up as your
equally good. They performed
equally well in most of our tests.
1st Kate
Licence LGPL/GPL Version 3.11
IDE. These apps are chock full of Whatever ground it lost to Sublime
bells and whistles, and their for not supporting macros, it gained www.kate-editor.org
developers aren’t thinking of for its keyboard friendliness and its The ultimate mild-mannered text editor with super powers.
stripping features, but adding more ease of use in deﬁning custom Kate is one of the best apps to come out of the KDE project.
and more and more. keybindings.
At the tail end of this test we have Kate’s success can be drawn 2nd Sublime Text
jEdit. Not only does it insist on from the fact that it offers the Licence Proprietary Version 2.0.2
using the proprietary Oracle Java maximum number of features with
Runtime Environment, it failed to minimal learning curve. Just ﬁre it www.sublimetext.com
install on our Fedora machine, and up and use it as a simple text editor, A professionally done text editor that’s worth every penny –
easy to use, full of features and it looks great.

“Kate offers the maximum features with 3rd Gedit
the minimum learning curve.” Licence GPL Version 3.10

the developer doesn’t actively or easily edit conﬁguration ﬁle with http://projects.gnome.org/gedit
Gets it done from Gnome. It’s a wonderful text editor and does
engage with its users. syntax highlighting, or even use it to
an admirable job, but the competition here is too great.
UltraEdit does little better. This collaborate and work on a complex
commercial proprietary tool programming project thanks to its
focuses on web developers, and project management capabilities. 4th UltraEdit
doesn’t offer anything to non- We aren’t pitching Kate to replace Licence Proprietary Version 4.1.0.4
developer power users that makes a full-blown integrated development
www.ultraedit.com
it worth recommending over free environment such as [insert your
Focuses on bundling conveniences for web developers without
software alternatives. favourite specialised tool here]. But offering anything special for general users.
On the third podium position we it’s an ideal all-rounder and a perfect
have Gedit. There’s nothing stepping stone to a specialised tool.
inherently wrong with Gnome’s Kate is designed for moments
5th jEdit
default editor, but despite all its when you need something that’s Licence GPL Version 5.1.0
positive aspects, it’s simply quick to respond, doesn’t www.jedit.org
outclassed by Sublime and Kate. overwhelm you with its interface A lack of support, lack of working on Fedora and a lack of
Out of the box, Kate is a more and is just as useful as something looking nice relegate jEdit to the bottom slot.
versatile editor than Gedit, and that might otherwise be overkill.

YOU MAY ALSO WISH TO TRY…
The default text editor that ships with your If you wish to follow the steps of Linux advanced editors like Emacs and Vim, such
distro will also be able to assist you with gurus, you could always try the revered text as the JED editor and Joe’s Own Editor, both
some advanced tasks. There’s KDE’s KWrite editors Emacs and Vim. First time users who of which have an emulation mode for Emacs.
and Raspbian’s Nano, for instance. KWrite want to get a taste for the power of Vim On the other hand, if you are looking for
inherits some of Kate’s features thanks to might want to consider gVim, which exposes lightweight code editors check out Blueﬁsh
KDE’s katepart component, and Nano has Vim’s power via a graphical interface. and Geany. They exist to ﬁll the niche
sprung back into limelight thanks to its Besides jEdit and Kate, there are other between text editors and full-fledged
availability for Raspberry Pi. editors that mimic the usability of veteran integrated development platforms.

www.linuxvoice.com 33
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EVEN MORE AWESOME!
ON SALE
THURSDAY Old Code
1 MAY Arise Sir Alan Turing,
genius coder,
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and 2hr 46min
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What a man.

Shopping
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a Windows refund?
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Find out before you
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It’s full of stars

GUI VS COMMAND LINE Use humble Python
to identify comets in
images taken by the
The command line will always have its awesome-sounding
proponents, but you can’t beat a nicely SOHO (Solar and
Heliospheric)
polished slice of graphical user interface satellite. Astronomy
for getting things done. Or can you? for the win.

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www.linuxvoice.com
HELLO HELLO WORLD!
HELLO
FEATURE CODE FOR ALL

WORLD!
D!
HELLO WORLD! WORLD! HEL

HELLO WORLD!
HELLO
WORLD!
D! HELLO HELLO H
HELLO WORLD!

WORLD!
WORLD! WORLD!
LO HELLO HELLO HE
LD! WORLD! WORLD! WO
HELLO WO

CODE FOR ALL
Programming isn’t just the domain of übergeeks – in the Year of
Code, everyone can get involved. Follow our guides and create
programs for the desktop, mobile phone and command line.

I
t wasn’t long ago that programmers Today you can tell someone at the pub With this in mind, we wanted to make
were viewed by the general public that you enjoy programming, and not be this issue’s cover feature all about
as strange wizards who spent looked at like you’ve just started coding. But not just as a generic
hours alone every day, tapping speaking Tagalog. introduction to a language or platform
incomprehensible gobbledygook into We’re all hackers on the Linux Voice – no, we wanted to show you how to do
black boxes on the screen. But in recent team, so we support every effort to useful things. So over the next nine
years, the perception of programming inspire people to code. It’s not all pages we have three projects explaining
as a hobby (and profession) has boring, complicated and alien like some how to make real-world desktop, mobile
changed enormously. Today it’s cool to people claim; coding can be fun, phone and command line applications.
hack the Raspberry Pi. Today it’s trendy stimulating and useful for developing As you’ll see, coding is for everyone, and
to write software for iOS and Android. future skills. you can code for any platform.

36 www.linuxvoice.com
CODE FOR ALL FEATURE

Desktop apps with Python
LLOFirst
WORLD!
step: building the required skills.

T
o kick off, we’re going to use Python, because Many good text editors
it’s an excellent all-round language which include syntax highlighting,
combines highly readable code with oodles of to make it easier to read
advanced features. Python code tends to be self- code – here’s Nano, for
example.
explanatory, so it’s a great way to dip your feet into
programming. We’ll start here with a quick overview of
the language; if you’re already familiar with Python, you
may want to quickly skim over this and then turn over

HELLO WORLD!
the page, where we start using it in our application.

A Python primer
Python is installed by default in most major

!
distributions, and it’s an interpreted language, so you
don’t need to compile your code before running it. In
the following examples, save the source code in plain speciﬁed text in quotes. Then we ask Python: if the
text format as test.py. Then run it like so: contents of x are 1 after the input, print one thing, and

ELLO
python test.py if the contents are not 1, (shown in the code as the
Let’s start with a very simple program: else statement) print something else. Why the if x ==
name = “Linux Voice” 1 though – why the double equals signs? Well, it’s just
print name + “ is the best Linux mag” to make a very clear distinction from x = 1 (a single

ORLD!
This demonstrates two aspects of the language: equals sign), which stores a number or line of text
variables and output. In the ﬁrst line, we create a new within a variable.
variable (like a storage space) called name – in
Python, you don’t need to explicitly state the type of a Funky functions
variable when you create it. In the second line, we print Next, we’ll dip our toes into functions. These are

ORLD!the contents of the variable to the screen, along with
another string of characters. Dead easy, right?
self-contained chunks of code that you can use to
build bigger programs. You can re-use them with
Let’s look at numeric variables: different parameters, to keep your code small and
x=1 easy to understand. For instance:
while x < 10: def multiplier(a, b):
print “x is”, x print a, “multiplied by”, b, “is: “
x=x+1 print a * b
print “Finished!” multiplier(6, 7)
Here we declare the x variable to contain 1 at the multiplier(10, 20)
start, and then begin a loop. While the contents of x multiplier(211, 2352)
are less than 10, we print the contents, and add one to Here, we ‘def’ine a function called multiplier, which
x. It’s important to note the indentation here: in Python, receives two numbers from the calling program, and
you use tabs to say which lines belong to a chunk of stores them in the variables a and b. This function
code. Here we say that the print and x = x + 1 lines then prints out the result of multiplication (using the *
belong in the while loop, because they’re indented. If operator). Note the tab indention again here, and also
you removed the tab from the x = x + 1 line, the note that this function is deﬁned at the start of the
contents of x would never be incremented in the loop, program, but it isn’t executed immediately – Python
so the loop would go on forever. starts execution in the non-indented part.
When the loop has ﬁnished, the program continues, So we can call our
so no indentation is required. (If you have loops inside
loops, you will have multiple levels of indentation.)
multiplier function with
different numbers, as “Python is installed by
Next, let’s move on to input and comparisons: shown in the three lines at default in most major
x = input(“Enter a number: “)
if x == 1:
the bottom of the code.
This is a trivial example Linux distributions.”
print “You entered 1” (you could just do the
else: multiplications in the main code), but it shows how
print “That wasn’t 1” you can build up programs from self-contained units.
Here we have our x variable again, and we call So, that’s the basics of Python covered – now turn
Python’s in-built input routine, which displays the the page and let’s do something useful.

www.linuxvoice.com 37
FEATURE CODE FOR ALL

A kiosk-like web browser
Write your own locked-down, ultra secure web browser.

W
ith our Python skills freshly prepped, let’s address = networkRequest.get_uri()
make a real application. Here we’re going if not “debian.org” in address:
to create a simple, and locked-down web md = gtk.MessageDialog(win, gtk.
browser than can only visit certain web pages and not DIALOG_DESTROY_WITH_PARENT, gtk.MESSAGE_INFO, gtk.BUT-
escape onto the big, bad web. Why would you do this? TONS_CLOSE, “Not allowed to leave the site!”)
Well, let’s say you’re setting up a web terminal for a md.run()
school, shop or museum, and you want to restrict md.destroy()
access to certain places. You could use a normal web view.open(“http://www.debian.org”)
browser, load it up with kiosk-like extensions and
ﬁltering proxies and hope that it’s secure, but clever view = webkit.WebView()
users may still be able to break out of the restrictions view.connect(“navigation-requested”, navrequest)
and cause trouble.
With our browser, we have just the bare essentials. sw = gtk.ScrolledWindow()
And even if setting up a web kiosk isn’t high on your sw.add(view)
list of things to do, it’s well worth following this tutorial
to see how a simple web browser is implemented. button = gtk.Button(“Back”)
button.connect(“clicked”, goback)
The code
Here it is – a whole web browser, contained within 35 vbox = gtk.VBox()
lines of Python. You probably don’t want to type this vbox.pack_start(button, False, False, 0)
out by hand, so grab it from www.linuxvoice.com/ vbox.add(sw)
code/microbrowser.py. This browser is set up to view
the Debian website at www.debian.org and nothing win = gtk.Window(gtk.WINDOW_TOPLEVEL)
else, but you can of course change that. win.set_size_request(800, 600)
import gtk, webkit win.connect(“destroy”, gtk.main_quit)
win.set_title(“Linux Voice browser”)
def goback(button): win.add(vbox)
view.go_back() win.show_all()

def navrequest(thisview, frame, networkRequest): view.open(“http://www.debian.org”)
gtk.main()
Now, we’re not going to write the entire HTML, CSS
and JavaScript rendering engine ourselves – that
would take months of hard effort and ﬁll many issues
of the magazine. No, we’ll leave that to WebKit, an
extremely capable rendering engine used in several
notable browsers such as Chrome/Chromium and
Safari. (Well, Chrome now uses the Blink rendering
engine, but this is based on WebKit.)
There’s a great Python module to interface with
WebKit, which we’re using here: you’ll ﬁnd it in the
python-webkit package in Debian and Ubuntu-based
distros. You’ll also need python-gtk2 for the interface.
So let’s step through the code:
import gtk, webkit
This is simple enough – it just tells Python that we
want to use the GTK module to provide the GUI
widgets, and the WebKit module for the rendering
engine. Then we have two functions:
def goback(button):
...
def navrequest(thisview, frame, networkRequest):
Here it is: our funky mega skillo web browser, which we can restrict to wherever we want, ...
written in just 35 lines of Python. How cool is that? We’ll come back to these in a moment, because ﬁrst

38 www.linuxvoice.com
CODE FOR ALL FEATURE

we need to set up some code to use them. So And here’s what happens
execution of the program begins here: if users try to stray beyond
view = webkit.WebView() the limits, as we deﬁned in
view.connect(“navigation-requested”, navrequest) the navrequest() function.
This is the heart of the program. We create a new
object called view (an object is like a variable, but it
can store and do a lot more), which is a WebKit
WebView. Put simply, this is a plain web browser view
– but with no buttons, no surrounding window, or
anything like that. It’s just a canvas to render web
pages inside.
The second line of this snippet is crucially Now we have to pack the button and WebKit view
important, and demonstrates a callback function. We into a single space, for which we use a vertical box
tell our web page view that if a navigation event widget in GTK:
occurs (ie the user clicks on a link), we should call the vbox = gtk.VBox()
navrequest function as included at the start of the vbox.pack_start(button, False, False, 0)
code. This function retrieves the address of the clicked vbox.add(sw)
link (networkRequest.get_uri) and checks to see if Then the following six lines, beginning with win,
debian.org is contained in the address. If not, we create a new application window, set its size, say what
show a dialog box and go back to the Debian home to do when the close button is clicked and set a title.
page. (Yes, this doesn’t make it 100% impossible for They also add the vertical box widget to the
people to escape www.debian.org, but you could application window and make sure that all of the
narrow down the allowed links even further with widgets inside it are visible. And the last two lines are:
regular expressions – that’s beyond the scope of this view.open(“http://www.debian.org”)
guide though!) gtk.main()
So, we have a web browsing pane which checks Here we tell the WebKit view to open a speciﬁc
links as they’re clicked. Next are these lines: page, and run GTK’s main event loop (where it
sw = gtk.ScrolledWindow() watches for button clicks

“There’s a great Python module
sw.add(view) and window operations
button = gtk.Button(“Back”) – we leave it alone from
button.connect(“clicked”, goback) here).
to interface with WebKit, which
we’re using here.”
As mentioned, the WebKit view isn’t attached to And that’s it! We’ve
anything yet – it just exists in memory somewhere crammed a lot in here, so
and that’s it. Here we attach it to a GTK scrolling if you have any
window so that users have scroll bars to move around questions, check out the websites for Python GTK
in the page. We create a new ScrolledWindow and (www.pygtk.org) and Python WebKit (https://code.
add the view object to it. google.com/p/pywebkitgtk). If you need further help, Want to delve into more
Then we create a new GTK button with the label post on our forums at http://forums.linuxvoice.com advanced Python topics?
Back, and also attach it to a callback function we and we’ll do our best to answer. See http://docs.python.org
wrote earlier: goback. So whenever the user clicks this for a wealth of tutorials.
button, the function goback is called. In that function,
we tell the view to step back a page (view.go_back())
and return to the main code.

Making Python apps directly executable
It’s easy to run our browser from the command line by
typing python microbrowser.py, but what if you want to
make it directly executable – so you can run it by simply
double-clicking on it? The trick is to add this to the top of
the ﬁle:
#!/usr/bin/env python
Now make the ﬁle executable (eg chmod +x
microbrowser.py) and run it (./microbrowser.py). This
extra ﬁrst line tells the operating system which interpreter
should be used with the following code, so you don’t need
to specify Python manually at the command line. In your
kiosk setup, you can easily trim down a desktop or window
manager to the bare essentials, and add a single launcher
pointing at microbrowser.py somewhere on your system.

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Mobile Linux
Don’t rely on the app store for software – create your own.

O
ver the last few years, Linux has taken over
the mobile computing marketplace. Android is
hugely popular, and there’s also Amazon’s Fire
OS, Firefox OS, Sailﬁsh OS, Tizen, Bada and soon
there’ll be Ubuntu Touch as well. Developing for
mobile platforms isn’t like desktop Linux, where the
same code is just repackaged for different distros.
This allows developers to make their apps ﬁt the look
and feel of the OS, but it also means that you have to
spend a long time developing for the different devices.
Fortunately, it doesn’t have to be this way. It is
possible to maintain a single codebase for use across
all the Linux-based mobile platforms (and a few
non-Linux ones like iOS and Windows Phone as well).
This way is Apache Cordova.
Apache Cordova is a framework that enables you to Don’t forget to consider the size of your computer screen
develop in HTML and JavaScript, then package it up when selecting what type of device to emulate. Modern
for each different environment. phones have a lot of pixels (often more than monitors).
While it may once have been suitable only for
displaying web pages, and perhaps a little interaction, the speed of natively compiled code. This means that
JavaScript has grown in to a powerful programming it’s still not quite there for some high-performance
environment. If you don’t believe us, have a look at applications, but it should be ﬁne for most cases.
these examples and see for yourself: The people at Mozilla know more than most about
The Unreal Engine 3 has been ported to JavaScript the power of HTML and JavaScript, and they believe in
and you can explore Epic Citadel in your browser: it so much that they built an entire phone operating
www.unrealengine.com/html5. system built around it.
Tearable cloth: http://codepen.io/suﬃck/pen/ Another great advantage of the HTML and
KrAwx. JavaScript approach is that it makes it really easy to
Freerider II: www.freeriderhd.com/t/1016-layers. get started. You can create simple pages in point-and-
With the canvas HTML 5 element, you can make 2D click HTML editors, then progress onwards as you
JavaScript graphics as complex as you like, and with learn more about programming and the environment.
WebGL, you can even harness the power of the
device’s GPU to create accelerated 3D graphics. First build
WebRTC can be used to set up a communication To get started, you’ll need the appropriate SDK for the
channel between two browsers, and Webaudio helps platform (or platforms) you’re developing for, and the
you add sound to your creations. We should point out appropriate version of Cordova (a full list can be found
that not all of these features are as yet possible with at cordova.apache.org/#download). In this tutorial
Cordova on all devices (even new ones), but it’s only a we’re going to use Android, as it’s the most popular
matter of time. mobile Linux, but you shouldn’t have any problem
The performance of JavaScript has long been transferring the work to a different platform such as
considered a problem for web app development, but Ubuntu Phone or Firefox OS. Sailﬁsh OS should be
in recent years, this has improved dramatically. Now, able to run Android apps, but we haven’t been able to
well-written JavaScript should perform at about half test this particular app.
You’ll need the SDK for every environment you’re
PhoneGap developing for. For Android, you can get it from
http://developer.android.com/sdk. You’ll get a ZIP ﬁle
Cordova is closely related to Adobe PhoneGap. In fact, that you can extract. You need to add the sdk/
they’re so closely related that they’re often mistaken for platform-tools and sdk/tools directories from this ZIP
one another. Ofﬁcially, PhoneGap is an implementation to your path. In the author’s environment, this was
of Cordova, but it doesn’t add much to the core release with the following command, though you’ll have to
in the same way a distribution of Linux adds a lot of
change it depending on where you unzip the SDK:
software around the kernel. For now we prefer to build on
a framework released by the Apache Software Foundation export PATH=$PATH:/home/ben/Downloads/adt-bundle-linux-
than one developed by Adobe. x86-20131030/sdk/platform-tools:/home/ben/Downloads/adt-
bundle-linux-x86-20131030/sdk/tools

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HTML and JavaScript for phones. In essence, it allows
Cordova pugins you to create off-line websites. This certainly has its
To access phone features, you’ll need to use plugins. uses, and many apps are nothing more than this.
The standard ones that come as part of Cordova are:
Accelerometer, Camera, Capture, Compass, Connection, Harness phone-speciﬁc features
Contact, Device, Events, File, Geolocation, Globalization, However, to be a true phone app, it should have
InAppBrowser, Media, Notiﬁcations, Splashscreen and
access to more of the phone’s features, such as the
Storage. There’s also a good selection of plugins available
at http://plugreg.com, should the standard ones not do GPS, accelerometer or ﬁlesystem. These aren’t
everything you need. available through normal JavaScript, but Cordova
allows plugins that expose certain features to its
JavaScript API. Take a look at the boxout above for
You’ll have to re-run this every time you restart your the standard plugins.
computer unless you add it to the .bashrc ﬁle in your As an example, we’re going to create a simple
home directory. weather forecast app. It’ll get the current location, then
Cordova is a node.js application, and you’ll need display a weather forecast for the area. We’ll also add
both node.js and npm for it to run. On Ubuntu and the ability to share it using social media, as apparently
derivatives, this can be done with the following code. If all good apps do this.
you’re using a different distro, check the available To start with, we need to get the HTML and
packages: JavaScript to grab a forecast based on latitude and
sudo apt-add-repository ppa:chris-lea/node.js longitude. Since everything is in the web technologies,
sudo apt-get update it’s far easier to test it out using web development
sudo apt-get install npm nodejs and tools than the Android-speciﬁc ones. Once
npm conﬁg set registry http://registry.npmjs.org/ everything’s working properly in a browser, you can
sudo npm install -g cordova then transfer it to Cordova and check it in Android.
Cordova works with a speciﬁc directory structure. We’ll start with a really simple HTML doc that just
To create a new project directory and appropriate grabs a forecast for London. Change the www/index.
subdirectories run cordova create myProject, where html ﬁle so that it contains:
myProject is the name of the new project. Now you <!DOCTYPE html>
can move into the new directory with cd myProject. <html>
Projects start off without any platforms. You can <head>
add as many as you like provided you have the SDKs <title>Weather Forecast</title>
installed, and Cordova will manage the builds for you. </head>
We’ll just add Android with: <body>
cordova platform add android Forecast:
And you can compile the example code (that each <br>
project is created with) using: <iframe id=”forecast_embed” type=”text/html” frameborder=”0”
cordova build android height=”245px” width=”245px” src=”http://forecast.io/embed/#l
In order to test your app, you either need an Android at=51.5072&lon=0.1275&units=uk”> </iframe>
device, or to use an emulator. To create a new </body>
emulated device, open the version of Eclipse that </html>
came bundled with the Android SDK. Go to File > New Save this as index.html in the www folder of your
> Other > Android > Android Project From Existing app. You could run this using Cordova on your phone
Code and select the platforms/android folder from or an emulator, but it’s easier at this stage to open it in
your project’s directory. Then do to Window > Android your normal web

“Another advantage of HTML
Virtual Device Manager and create a new virtual browser.
device. Once this is set up, you can run the project 51.5072, 0.1275 are
from the command line with: the coordinates we’ll use
and JavaScript is that it makes
it really easy to get started.”
cordova emulate android (this is in London). This
Some of these work far better with a physical grabs an iframe with the
device than an emulator, so if you have an Android current forecast from
phone or tablet, it’ll be easier to follow the rest of this forecast.io. In order grab the forecast for the current
tutorial on that. The method for doing this varies location, all you need to do is create an iframe with the
depending on the version of Android you have. Visit right latitude and longitude.
http://developer.android.com/tools/device.html for Writing iframes in JavaScript is easy, since you can
more details. Once you’ve set up your phone, and manipulate the HTML inside an element. All you need
connected it to your computer via the USB cable, you to do is create a <div> </div> that you can put the
can load and run the app with: iframe inside. Now we’ll add the ablity to switch the
cordova run android location between London and New York. First change
In its basic state, this enables you to package up the code between the <body></body> tags to:

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Forecast:
<div id=”location”></div> Signing apps
<div id=”forecast”>Select Location</div> Cordova can build a ﬁnal version of your app using the
<br> --release option to the build command. However, this won’t
<button onclick=”getForecast(51.5072, 0.1275)”>London install on any phone until it’s been signed. You can create
a key for signing it yourself, so this isn’t a restriction on
Forecast</button>
distributing your software. There are details of how to do it
<br> here: http://developer.android.com/tools/publishing/app-
<button onclick=”getForecast(40.6700,73.9400)”>New York signing.html.
Forecast</button> You can distribute your app without an app store if you
<br> want. Just send the .apk ﬁle to people and (as long as they
have sideloading enabled) they can install it themselves. Of
<div id=”getlocalforecast”></div>
course, you can put your app on the main Google Play store
<div id=”forecastDetails”></div> if. You’ll ﬁnd details about how to do this here:
This has two divs with different IDs that we’ll use http://developer.android.com/distribute/googleplay/
now, and some more that we’ll use in a bit. We’ll use publish/preparing.html.
JavaScript to update them to what we need them to Google Play isn’t the only Android app store though. If
you open source your app, you may wish to add it to the
be. The two buttons call the getForecast(latitude,
F-Droid store. Take a look at www.f-droid.org for details.
longitude) function that we’ll now deﬁne.
Add the following just before the </head> tag:
<script type=”text/javascript”> become clear later. Again, you can test this out in a
function getForecast(latitude, longitude) { web browser and it should work ﬁne.
var element = document.getElementById(‘location’);
element.innerHTML = ‘Latitude: ‘ + latitude + ‘<br />’ + Not just a website!
‘Longitude: ‘ + longitude + ‘<br />’; Now let’s add the phone-speciﬁc stuff. Cordova uses
window.iframeurl=’http://forecast.io/embed/#lat=’ + latitude + plugins to add access to different features, so in order
‘&lon=’ + longitude + ‘&units=uk’; for our app to be able to access the location, we need
showSimple(); to use the Geolocation plugin. This is done by running
} the following command in the root directory of the
function showSimple() { web app:
var weather = document.getElementById(‘forecast’); cordova plugin add org.apache.cordova.geolocation
weather.innerHTML = ‘<iframe id=”forecast_embed” This will add it to every platform you have registered
type=”text/html” frameborder=”0”’ + as long as the plugin works on that platform.
‘height=”245px” width=”245px” src=”’ + window.iframeurl + In order to access the Cordova features, you need
‘”> </iframe>’; the cordova.js script, so add the following line just
} below </title>:
</script> <script type=”text/javascript” charset=”utf-8” src=”cordova.
This splits the execution up into two stages. The js”></script>
ﬁrst sets the contents of <div id=”location></div>, With this in place, you can add the following
and the variable window.iframeurl. By deﬁning this functions inside your main <script> tag:
The documentation at variable as attached to window, it makes it available to document.addEventListener(“deviceready”, onDeviceReady,
http://cordova.apache.
all our functions, rather than just local to the current false);
org/docs/en/3.3.0/ is a
function. The same effect could have been achieved function onDeviceReady() {
great place to ﬁnd help.
It has guides for all the by using a global variable. localforecast = document.getElementById(‘getlocalforecast’);
standard plugins including The second function sets the <div id=”forecast”></ localforecast.innerHTML = ‘<button onclick=”getLocal()”>Local
comprehensive code div> to be an iframe with the appropriate location. The Forecast</button>’;
samples. reason we’ve split this up into two functions will }
function getLocal() {
navigator.geolocation.getCurrentPosition(onSuccess,
onError);
}
function onSuccess(position) {
getForecast(position.coords.latitude, position.coords.
longitude);
}
function onError(error) {
alert(‘code: ‘ + error.code + ‘\n’ +
‘message: ‘ + error.message + ‘\n’);
}
The ﬁrst line listens for the deviceready event. This
tells it to run the function onDeviceReady once the

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app is running properly. We’ve added this to stop The app in action.
people trying to get a local forecast too soon. Unfortunately, that’s the
The function getLocal can just call navigator. best weather we’ve had in
geolocation.getCurrentPosition(). We’ve passed it months.
two parameters: the ﬁrst is the name of the function
to call if it succeeds in getting the location; the second
is the function to call if there’s an error.
onSuccess passes the returned values on to
getForecast(), while onError() displays the error
message as a JavaScript alert.
With all this entered and saved, it’s ready for its ﬁrst
proper test. To compile and run it, enter the following
terminal commands in the app’s root directory:
cordova build android
cordova run android
If you’ve got your phone attached, this will send it
across and open it on your device, otherwise it’ll start
the emulator.
You’ve just created a phone app! It’s quite limited,
but accesses one of the phone’s features. Since all
good mobile applications have social features, we’ll
add this facility now. We won’t make speciﬁc links to
social media, but use the phone’s features to share
the forecast with other applications. The user can
then pick how they want to share the forecast.

Engage Twitbook
As you may have guessed, this feature comes from
another plugin, but this time it’s one that’s not part of
the main Cordova release. You can add plugins detailed forecast. Fortunately, Forecast.io does most
straight from Git, so in a terminal in the app’s root of the hard work on this. The only thing we have to do
directory, enter: is change the size of the iframe.
cordova plugin add https://github.com/leecrossley/cordova- You’ll need to adjust the showSimple() function and
plugin-social-message.git add showDetails() as per the following:
As with the previous plugin, this exposes more function showDetails() {
JavaScript functions that we can access. In this case, var weather = document.getElementById(‘forecast’);
it’s socialmessage.send(). Using this, you can interact weather.innerHTML = ‘<iframe id=”forecast_embed”
with the other apps on the phone. Add the following type=”text/html”’ +
function inside the <script></script> tags: ‘frameborder=”0” height=”245px” width=”500px” src=”’ +
function share() { window.iframeurl +
var message = { ‘”> </iframe><br><button onclick=”showSimple()”>Hide
subject: “Weather Forecast”, Details</button>’;
text: “Check out my local forecast”, }
url: window.iframeurl
}
function showSimple() {
var weather = document. “Cordova uses plugins to
window.socialmessage.send(message); getElementById(‘forecast’); access different features – we
need the Geolocation plugin.”
} weather.innerHTML =
You’ll also need a button in the body of the HTML to ‘<iframe id=”forecast_embed”
access it. However, you can’t share the forecast until type=”text/html”’ +
it’s received, so the button should only appear once ‘frameborder=”0” height=”245px” width=”245px” src=”’ +
there’s a forecast. The easiest way to do this is by window.iframeurl +
adding the lines: ‘”> </iframe><br><button onclick=”showDetails()”>Show
var weatherDetails = document.getElementById(‘forecast Details</button>’;
Details’); }
weatherDetails.innerHTML = ‘<button onclick=”share()”>’ + Of course, it still looks a bit plain, and you could add
‘Share this forecast</button>’; many more options, but this isn’t a tutorial on creating
to the end of the getForecast() function. the perfect weather forecasting app, it’s a tutorial on
We’re almost done with our app now. The last little getting started with mobile Linux development. It’s up
feature we’ll add is the ability to show a simple or to you to decide what to do with it now.

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Programming the command line
Automate everything, then sit back and relax as your computer takes care of itself.

S
o far we’ve talked about programming in terms Lets take a look at this in detail. The ﬁrst line is
of making new software. However, called a shebang, and it tells the computer that this is
programming can also be a way of linking a Bash script and that it should be executed with the
together existing software to automate tasks. In this command /bin/bash.
way, you don’t create anything that you didn’t have The second line does two things. First, it executes
access to before, but you make it much easier to use. the ﬁnd command, which we explained above; then it
Let’s take a really quick example. Suppose you’re a pipes the output of the command into a while loop.
writer, and you save all your work in ODT ﬁles. These Piping (which is done using the character |) is an
ﬁles are scattered about your home directory essential feature of Bash programming, and it can
(because most writers aren’t organised enough to also be done on the command line. It just tells the
keep their ﬁles in one place), and you want to do a full system to take the output of one command and feed
backup of all your writing. it into the next. As another example, if you’re using a
There are many ways you could do this. One of the terminal and you’re in a directory with loads and loads
easiest is to create a simple program that searches of ﬁles, it sometimes doesn’t work very well if you just
for all the ﬁles and copies them to a remote computer. run ls to list them (the ﬁlenames can go off the top of
Bash is the shell that most Linuxes use, and while the screen). Instead, you can pipe the output into a
many users know it only as a command line text viewer such as less with:
environment, it’s also a programming language in its ls | less
own right. We can use it to link up a series of Linux This allows you to scroll up and down through the
commands to execute based on the information that list of ﬁles. You can also do it for other commands
other commands provide. In this example, we’ll use that produce a lot of output.
the command:
ﬁnd /home/ben -name “*.odt” Digression over
To ﬁnd all the required ﬁles. Not surprisingly, the Back to our backup script though. In this case, the
ﬁnd is command for ﬁnding things, and is far more program outputs the result of the ﬁnd command into
powerful than this command shows. Using other while read f. This slightly cryptic statement starts a
options, you can ﬁnd ﬁles based on the time they were loop for every line in the output and tells it to store the
created, the time they were last modiﬁed, and a whole line in the variable f. In other words, everything
host of other things. See the man page (type man ﬁnd between do and done is executed once for every line
in a terminal) for more details. in the output of the ﬁnd command, that is:
We’ll then copy all the ﬁles into a backup folder cp -f “$f” /ben/backup
(which could be on an external drive). The bash code The $f tells Bash to insert the line output from the ﬁnd
to do all this is: command here. It’s in quote marks because otherwise
#!/bin/bash ﬁlenames with spaces in them will cause problems.
ﬁnd /home/ben -name “*.odt” | while read f; This is a really simple example, but it shows how
do you can build up scripts in Bash. The two main ways
cp -f “$f” /home/ben/backup of combining commands are piping output, and
done running loops over multiple lines. With these two
You’ll need to change /home/ben to the location of techniques, you can combine all the command line
your home directory. tools in Linux into your own powerful scripts.
Before running it, you have to make the backup
directory with:
mkdir ~/backup
If you save this program as backup.sh, you can run
it from the command line with:
bash backup.sh
As long as you are in the same directory that you
saved the ﬁle. Alternatively, if you make it executable
with the command:
chmod a+x backup.sh
you can run it with:
./backup.sh
Explain Shell (www.explainshell.com) is a tool for linking Sometimes, it’s not enough just to send the output
bash commands to their help text. of one command straight into another. Sometimes

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you need to make a decision based on the output
that’s being processed. For example, what if you didn’t Books
want to copy all ﬁles straight into the backup Bash scripting is incredibly, but can also get quite technical.
directory? What if you wanted to sort them and put If you’re interested in taking it further, there are loads of
different ﬁles in different places? good books on the subject. The Linux Command Line and
In the next example, we’ll ﬁnd all LibreOfﬁce Writer The Advanced Bash Scripting guide are both excellent
and Calc ﬁles (ODT and ODS respectively) and all MS choices. The latter is a bit more technical than the former.
What’s more, the both have e-book versions that are free as
Ofﬁce Word and Excel ﬁles (DOC/DOCX and XLS/ in zero cost and free as in speech. You can get them from
XLSX respectively), and split them into word www.linuxcommand.org/tlcl.php and www.tldp.org/LDP/
processor and spreadsheet folders. abs/html/index.html respectively.
This can be done with the following:
#!/bin/bash
ﬁnd /home/ben $ -name “*.odt” -o -name “*.ods” -o -name
“*.doc” -o -name “*.docx” -o -name “*.xls” -name “*.xlsx” $ |
while read f;
do
if [[ $f == *.odt ]] || [[ $f == *.doc ]] || [[ $f == *.docx ]]
then
cp -f “$f” /home/ben/backup/wordprocessor
ﬁ
if [[ $f == *.ods ]] || [[ $f == *.xls ]] || [[ $f == *.xlsx ]]
then
cp -f “$f” /home/ben/backup/spreadsheet
ﬁ
done
The Bash if command allows you to execute a code
block only if a particular condition is true. It’s both
hugely powerful and quite complex. Used like this
(with [[ string1 == string2 ]]) it matches ﬁlenames,
and you can use asterisks in the same way you can at
the command line, so *.doc matches any ﬁle that
ends with .doc. The || is used to group multiple
conditions together so that the code block is run if any If you prefer your books in paper form, see The Linux
one of them is true. Command Line website for purchasing options.

Running automatically
Writing scripts like this can really simplify general You should now see ‘GNU nano’ In the top-left
tasks like backing up data, but wouldn’t it be great if corner. Depending on your distribution, you may ﬁnd
you could automate running them as well? that you already have some scheduled tasks, you may
Almost all versions of Linux (and, for that matter, have a blank ﬁle, or you may have some lines that
Unix in general) come with a tool called crontab. The start with a # (these are
name doesn’t give much away, but it’s for scheduling
tasks to run at certain times (it’s named after Chronos,
comments).
To schedule tasks, you
“Sometimes it’s not enough
the Greek god of time). There are only really two need to add a line to this just to send the output of one
options that you need to know: -e and -l. The ﬁrst is
used to edit scheduled commands, and the second is
ﬁle that tells it what to
run and when. Schedules
command into another.”
used to list them. are broken up into ﬁve
So, to set up our script to back up commands, run: parts, each of which can be a number or an asterisk.
crontab -e For example:
This will start a text editor (usually either Vim or 0 2 * * * /home/ben/backup.sh
Nano). If blank lines at the bottom of the ﬁle are The ﬁve scheduling segments represent the minute
displayed as ~, then it’s probably opened in Vim. This of the hour, the hour of the day, the day of the month,
is a powerful editor, but it can be quite confusing if you the month of the year, and the day of the week. An
haven’t used it before. If you want to switch to asterisk means ‘every’. The above line will run the
something easier, exit Vim by pressing Escape, :, Q backup script at 2.00am every day. If you were more
and !. They you can tell the system to use Nano cautious, you could run it every hour with:
instead by running: 0 * * * * /home/ben/backup.sh
export EDITOR=nano Or you could run it twice a day with:
crontab -e 0 0,12 * * * /home/ben/backup.sh

www.linuxvoice.com 45
INTERVIEW CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL

EDUCATION
EDUCATION
EDUCATION
Teaching the world to code is a noble goal, but
how is it going to work in practice?

T
wo years ago, when the it. To find out more we travelled
Raspberry Pi launched, it was west to Manchester, venue for the
with the intention of second annual Jamboree – a
improving IT education in the UK. festival of educators, makers and
Since then more powerful, better messer-abouters focussed on
connected or cheaper boards have highlighting how engaging the Pi
come onto the market, but the Pi can be. There, we met 75% of the
retains its position as the white Raspberry Pi Foundation’s education
knight of ICT teaching. team – Ben Nuttall, Clive Beale and
Why? Because of the community Carrie Anne Philbin – to discuss IT
of users that has grown up around teaching in the UK.

So, Raspberry Pi education computing, to teach them how to use a
team, we were saying earlier computer. No politician has stepped in
that the obvious place to start is to say this is not the case and they
with the UK government’s Year of haven’t asked the teachers who would
Code initiative, but that seems far tell them this isn’t the case. And that’s having an impact. It’s just very different
too negative to begin with! the problem. Where are the teachers? to what I was seeing before.
Carrie Anne Philbin: Yeah, but Where are the people who are actually Clive always says there’s a massive
there’s so much to say about it! teaching? difference between teaching and being
Clive Beale: I mean the main issue is a teacher. There are a lot of people we
how the media portray computing, Carrie Anne, you’ve only just talk to who run Raspberry Jams,
which is a brilliant, creative, rigorous, left teaching to join the workshops, Coder Dojos and that kind
hard, challenging, fun thing, and they Raspberry Pi Foundation – you must of thing, and they always say ‘Oh, it’s
just reduce to this ‘code’. You start to have some insights into the really easy, you just do this, this and
hear things like ‘We must learn to code’ difference between the reality of this.’ And that’s great, but you’ve got
and ‘You better learn code or you’re a teaching in schools and how the kids coming to you who want to learn
rubbish teacher.’ Which of course is not latest government wheeze imagines this stuff. Imagine a class where you’ve
the case at all; it’s so much more than it to be? got a bunch of kids who aren’t
that. And so the teachers are running Carrie Anne: It feels like a lot longer interested or engaged by this subject
around now thinking the sky’s falling than two months, it feels like an and actually teaching is much harder…
because they think that by September eternity! Teaching is so fast-paced, in Clive: Maybe 15-year-olds on a Friday
2014, if they can’t code, then they’ve that you’re seeing the results of what afternoon…
failed and they’ll think their kids have you’re doing in class straight away, Carrie Anne: …yes, a six-period day,
failed, and it’s a really bad message. whereas being out of the classroom for end of the week…
There hasn’t been a simple message to the past two months and working for Clive: …Ofsted saying, ‘Why haven’t
say this is not the case. You can get out the Foundation, I can’t actually see the your kids developed after 20 minutes in
into the playground with some chalk impact I’m having, but obviously people your lesson? Why haven’t they
and make a maze and do some are talking to me and saying I am progressed?’ It’s very different.

46 www.linuxvoice.com
CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL INTERVIEW

“The Raspberry Jams have done
an excellent job of bringing people
together from all walks of life.”

So you have some idea of how with the new curriculum. I mean, the Clive: It would be nice to see [what
things should be done because work I did as a teacher producing the happened with Sonic Pi] as a
of your recent experience. Are we, in Sonic Pi was a team of work. That was microcosm of how these things
general as a society, doing the right because I worked with – yes, an actually happen. So if an academic has
things to foster the next generation? academic – but he was an expert. He a brilliant idea and they’re very good at
Carrie Anne: I think so. I think what’s wanted to develop a teaching what they do, they should feel that they
been really nice about the Raspberry Pi environment that I could use with my can come to a teacher and say ‘How
community is that is gives back to the students to teach tech-based can we make this useful in the
community. So there are experts, there programming in a fun and engaging classroom?’, ‘How can we get
are people who love what they do, who way, that engaged both genders and assessment in there?’, which schools
are reaching out to teachers and engaged both low- and high-ability need, frankly, ‘How do we make it
reaching out to children by running students. It’s a tech-based robust?’, ‘How can we test it?’.
workshops and clubs and things. And programming language, which is Isn’t that a weird idea, to actually ask
it’s actually that collaboration that important at Key Stage 3 [pupils the people that teach how we should
produces the best materials and between the ages of 11 and 14], where do that? It hasn’t happened really. But,
produces the best way to move forward you need to not just be able to teach yes, as Carrie says, we’re going in the
Scratch, you need to teach a tech- right direction, certainly. The
based language that’s a nice bridge community and third parties are doing
“The community and third between Scratch and something like
Python, which we can teach later on.
more to push it along.

parties are doing more to push So, yeah, I think we are moving in the From someone outside a little
ICT education along.” right direction. It would be nicer if the
powers that be…
bit, it kind of looks like a
community has sort of

www.linuxvoice.com 47
INTERVIEW CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL

like Ben and Dave (Honess).
Carrie Anne Philbin’s
Ben: Yes, some people have ideas for
book, Adventures
In Raspbery Pi, is things and think this could be an
reviewed on page 26. engaging exercise, but they may not
know exactly how to deliver it, or how
it’s going to work. They might not know
how exactly a teacher is supposed to
produce something to use that, but
they have an end goal and working with
someone else can help achieve that.
Clive: Yeah, you’re right, the real key is
the mix. So you’re getting teachers and
engineers and developers and families.
Before, they might have been on a Linux
user group, they might have been a
teacher group, and you’re just bringing
a bunch of different people together
and that just (to use a horrible word!)
synergises stuff.
(Everyone LOL)
Clive: Yes, I did it! I said synergises! I’m
spontaneously developed around Carrie Anne: Well, teachers tend to buying a copy of the magazine now.
the Raspberry Pi. Has this suddenly generally get together through things Carrie Anne: There’s something that
mushroomed, or has it always been like TeachMeets and through Twitter, comes about from getting all those
there and it’s just become more and those kinds of chat tools. There are different types of people together. It
obvious now? ways that you can get together, but breeds this wonderful learning
Carrie Anne: I think it’s always been that’s more talking about teaching environment that you cannot
there. I was a teacher, so when practice. Like the different ways you reproduce. Like, Ben was running a
Raspberry Pi first came out I got one. I can use a sentence. It’s very teachery, it Picamera workshop this morning. So
thought, this is brilliant! Someone’s wasn’t specific to teaching computing. that was run by people who run Jams
developed something for education. A Clive: I think that hardware-wise, the who are from industry. And what was
Linux box that we can use in the Raspberry Pi was in the right place and really nice is that there were teachers
classroom. You can mess about with it, the right time. and there were people who had come
it’s cheap, it’s brilliant! Ben Nuttall: The Jams have done a for the Jamboree from industry that
And then I was like, right, so where really good job of bringing people were helping the teachers do stuff. And
are the resources to go with it? Ah, together from all walks of life. The there was this environment that was
there aren’t any. So where can I go and people, like myself, who were attending like, it’s OK to not know something, it’s
find some? The first obvious place was user groups and who are interested in OK to ask a question, it’s OK to get it
Raspberry Jams. There are people tech and really passionate about it, wrong and make mistakes. And that’s
running events where they’re doing have got a chance to share that interest really powerful, because sometimes
stuff. So I thought I’ll go along and with the wider community. There were
speak to some people, and see what’s
available. And it was through this that I
families coming in, teachers coming in,
and they were just sharing what they “You’re bringing a bunch of
met people to work with, and they’d were doing and the skills they already different people together and
that just synergises stuff.”
formed that themselves, the had, and I was already programming in
enthusiasts from throughout the Python and things like that just on the
community around the Raspberry Pi. desktop, and the Pi came along and it
Clive: It’s been a focus, hasn’t it? opened up this way of plugging into the teachers are afraid perhaps of saying
There’s been a lot of people sort of real world and all the other things the Pi they don’t know.
hanging around, saying ‘Look, I like brings with it. Just being about to use Ben: So at this workshop, we gave
tinkering, I like messing, I like coding, I those skills and pass them on, I got people an intro to building a real
like making’, and this thing appeared involved in education through that. application around the camera. So it’s
that was cheap and cheerful and not just ‘Oh, there’s a camera and you
fantastic to play around with. It was So you weren’t a teacher can take pictures’. It was ‘OK, let’s plug
waiting to happen really. before then? in a button, and attach that to the Pi
Ben: No, I was a software developer. and let’s make that be the button for the
Was there anything equivalent Carrie Anne: This is what’s great camera’. And just a simple intro like that
to Raspberry Jams before the about the education team at Raspberry opens up a world of possibilities.
Raspberry Pi came along to bring Pi. It’s 50% ex-teachers and 50% Sometimes a lot of these things, such
people and teachers together? software developers. We need people as Jam, just gives you a lot of

48 www.linuxvoice.com
CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL INTERVIEW

Clive Beale (left) and Carrie Anne
Philbin were both teachers until
recently, while Ben Nuttall comes from
the world of software development.

inspiration. Or if you see something in a make one. And some of them would you’ll find that quite often you’ll get
magazine or online, or on Twitter, and need a lot more guidance. what are classed as low ability kids who
you think somebody’s done that with just rip into that and do fantastic things
the Pi, I’d really like to do that project in Are there some kids that just because it’s the first time they’ve been
my garden or I’d like to do that myself don’t get it at all? allowed to get ideas out of their heads
and twist it and use some of the Ben: I think there’s something for and make something with it, whereas
libraries they’ve used or, use some of everyone, but they might not find it before, if they’ve had problems with
the codebase they’ve used and take it in straight away. If you delivered a term’s writing and numeracy, they haven’t
their own direction. worth of content for a class, with a been able to do that.
Clive: Like maybe it’s not a button; good scope of different projects, I’d be There are case studies with young
maybe it’s a sensor for when your surprised if there was one kid that boys who aren’t very good at reading
parents walk into your bedroom, and it wasn’t interested in any of it or didn’t and writing but they start telling stories
then tweets it as they walk in. find any of it engaging. when you give them an environment
Ben: And everyone’s got a different way Clive: It’s almost an antidote for kids where they can actually do these
of thinking. If you’re in classroom of 30 not getting it. With teaching music, things. So it’s not that they don’t get it.
kids and you show them how to make a you’ll have people that are level 5 or 6 There’s something for everybody.
button do this, each of them is thinking while others can’t read music. Because
‘Oh I can make a such and such’. They’ll computing is creative and engaging, we Pre-Raspberry Pi, in the dark
all have a different idea. And some of don’t all have to become master coders. ages of about ﬁve years ago,
them will just go straight home and With Scratch, it’s a visual language and before the ICT revolution, what
would those children be doing?
Would they have responded to ICT in
school at all?
Carrie Anne: In a classroom, you have
a network of computers that are all on
lockdown. You’ve got your network
administrator and team of technicians,
and they do a wonderful job and I
certainly wouldn’t slate them – I was a
technician once. But we were living in a
time where you had to lock down the
internet, which I disagree with, I think it
should be open. And all the computers,
you can’t execute any files on them, so
you can’t actually teach any
programming on them. So that was a
problem for me.
This year’s Jamboree was held in
conjunction with the Education
Innovation Conference and Exhibition. Is that changing?
Carrie Anne: I think it is

www.linuxvoice.com 49
INTERVIEW CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL

changing, and will change with the new them exactly what they have to do with government got involved and it
curriculum. For me as a teacher, what it instead of letting them explore. snowballed really.
was great when the Raspberry Pi came Whereas with the computing thing, Clive: Scratch was a big word-of-
along is that I didn’t actually need those especially things like Scratch, just lets mouth thing. It was about mid-2000
computers around the outside of the them think, ‘OK, I can do a movie, I can when it came out, and suddenly you
classroom any more. I didn’t need to do a little flip frame animation, or you just found that any teacher worth their
seek anyone else’s permission any know what, I can actually make a salt was using it for their ICT curriculum
more to do what I wanted to do. Here’s game’. And then suddenly they’re doing because it taught about control.
my box full of Pis, let’s just get them stuff that they haven’t had the Carrie Anne: HTML as well. HTML
out. You can break it. And that’s OK, you opportunity to do. has been on the curriculum for years.
just flash it and start again. Carrie Anne: That old ICT curriculum We’ve been teaching HTML in Notepad
Clive: In 1997, they put the C back in was about 12 years out of date. It was for years.
ICT [Information and Communications created and it wasn’t updated.
Technology] and suddenly it became What are going to be the big
this thing that you had to teach. The Obviously quite a lot has things pushing it forward over
curriculum wasn’t really that bad. A lot changed in computing the next few years?
of people moan about it, but if you education according to the media Carrie Anne: I think more of the same
actually sat down and read it, it was over the last couple of years in the really. It’ll be teachers, it’s always the
quite flexible and did let you take control UK. If the curriculum has only just teachers. They’re the ones who come
and make programming and coding changed, what is it that has been to the Jamboree and this kind of thing,
interesting. But because resources are driving improvement? and learn from people like Ben and that
so important to schools, you just ended Carrie Anne: I think the teachers. sort of collaboration. That’s where it
up doing the easy things. They’re the ones in the classroom who starts. The teachers see what can be
have to teach the curriculum. When I done, and they start doing it, and there’ll
But when you said about kids became a teacher, I was already be more of that. And there are initiatives
using Scratch and becoming working in a school and I kept putting like code clubs, and the Master
motivated to do other things, that off becoming a teacher because the Teachers are great.
would never have happened before curriculum bored me. Clive: Teachers are meeting up more
the Raspberry Pi came along. But then I realised that, when I when before they may not have been
Clive: Yes, it was more just following actually got into the classroom, I was getting together.
what the teacher said, ‘And now we’re able to put my own spin on it. I think it Ben: And as well as there being more
going to write a letter to the cinema started with the teachers –the people content, I think there’ll be convergence
using Microsoft Office’ or something. who are saying: “We want a new of a lot of this stuff. So, because the
That’s like giving someone a Ferrari and curriculum, we want to teach this”. I Raspberry Pi doesn’t have any official
saying you’ve just got to drive in this think it started there, and then industry resources right now, some people are
room for half an hour. So you’ve given picked up on what was happening and going off and writing their own. I think
them this fantastic tool for exploration they wanted to get more industry they’ll be a convergence of people
and creativity, and then you’re telling experts involved. And then the pulling their ideas together and there’ll
be a more centralised system for that.
And we’ll be helping the community out
with that.

You haven’t mentioned
government policy, or anything
like that at all. Is that a negative
thing or just by-the-by?
Clive: I was at the Westminster forum
yesterday and they had a chap from the
Department for Education there, and I
couldn’t resist it, so I got the mic and
said: “You haven’t really taken it
seriously have you?” He turned round
and said, we have really taken it
seriously. This idea that we can just
bring in a new program of study and
say ‘Oh, aren’t we wonderful’, because
[Google Boss] Eric Schmidt has made a
speech, and suddenly we’ve made it all
better for you. But you haven’t, you just
seemed to have done something that a

50 www.linuxvoice.com
CARRIE ANNE PHILBIN, CLIVE BEALE AND BEN NUTTALL INTERVIEW

mark students’ work. They need time.
Clive: Science is a good example. If
you’re a chemistry or biology teacher at
secondary level, there’s a scheme
where you can re-skill to physics and
they will give you free periods, a huge
bursary, and they’ll also take you off
timetable one day a week to go off and
go to other schools and retrain, and
maybe pay for the cover.
This is the government doing this,
and if you do this, this and this, you
come out as an accredited physics
teacher. So they took that seriously, but
yet here’s a brand-new subject and
they’re expecting people just to pick up
and run with it, the preparation is
completely inadequate.
Carrie Anne: But it’s not just time to
learn something, it’s also time to go and
meet industry people. Like go to a
company and be in there and work and
learn from them, and see what the
world is like. Because some people,
lot of teachers are now scared of. So skills taskforce, and which I’m part of they went through education, went to
there’s a lot of work to do, and we’re the team. We’re looking at where the university and became a teacher, so
really positive. But no, the government skill shortages are and what digital they’ve never left this school
have not, in my personal opinion, given skills are needed. Because there’s going environment and they’ve got no idea of
the money or the support or the to be a whole group of kids who are what the world of work is like.
thought behind this. now 14 to 16 who are going to leave the Ben: I think there are some people in
If you go to Jersey, there’s such a education system who haven’t had new the current government who seem to
great contrast with what’s been programs like these. They were on the think there should just be this package,
announced for England. They’re going old program, so we’re looking at who and this is what you should deliver as
to spend £6 million on the 100 missed out and what we can do about your syllabus this year. Everyone is
thousand people who live on the island that. So hopefully that report will inform treated the same. Each teacher has
– that’s the size of Cambridge. Jersey government policy. their own class, and they’re all different,
has the infrastructure, fibre to the door with different ways of engaging their
in every school, linking into businesses, If there’s one thing you could interest. It needs to be tailored, so the
a £2 million training budget for change about government teacher needs to take that material, and
policy, what would it be? perhaps look on the Raspberry Pi site in

“Every teacher needs more
Clive: It really is to do with support for the next year and say, well this one
teachers. This idea that teachers – looks quite suitable for my class, or this
time off their timetable to especially primary school teachers one might be a good one to do.

develop their skills.”
where you have to teach a range of Clive: The government also does not
subjects – would be able to suddenly understand that this is long term. So if
go off, and teach themselves from the you’re going to start teaching five-year-
teachers… That’s practically what the third-party resources just doesn’t work. olds about algorithms and a bit of code
government pay for the whole of Carrie Anne: Time. One of the biggest and Scratch, what happens further
England with 53 million people. recommendations that I would say is down the line? The secondary school
So, has the government taken the time. Every teacher needs more time teacher will be saying, I can’t teach
scale of the task seriously: no. I think off their timetable to develop their skills, them Scratch anymore, which is what
they’ve completing underestimated especially in an area like this that they we do in Year 7 at the moment.
what’s involved. They thought the perhaps think they’re weak. Because it It’s a long term challenge, and things
teachers would just pick it up and have takes a while to set things up and start will continue to change over the next
the time and resources, which we don’t your learning. As a teacher, you get a several years until that pipeline
have the time for. 30-period timetable, you’re teaching for becomes full. And they’ve said “Here’s
Carrie Anne: Maggie Philbin about 22 lessons of that with about 7 £2 million, do some training for
[presenter of television programmes free periods, but some of those you’ll be September 2014”. What’s 2014 got to
Tomorrow’s World and Bang Goes The covering for another lesson and some do with it? This is five, six, seven years
Theory] has been leading a UK digital of those I need to plan my lesson and down the line.

www.linuxvoice.com 51
FEATURE MUNICH

Munich city council has migrated 15,000 workers from Windows
to Linux. Mike Saunders and Graham Morrison visited the city and
learned just how upset Steve Ballmer was…

“One of the biggest aims of LiMux was
to make the city more independent.”

H
irschgarten, in the west of the last decade. Migrating workers of
Munich, is one of Europe’s biggest Germany’s third-largest city was no easy
beer gardens, with over 8,000 task and there were plenty of hurdles along
places to sit. It’s a spectacular sight in the way, but by and large the project has
summer: hundreds of benches as far as been a storming success.
the eye can see, trees providing some We’ve been following the progress of
shelter from the heat, and a vast number LiMux (Linux in Munich) for years, and now
of people relaxing and enjoying the city’s that the project is effectively complete, we
famous beers. decided to visit the city and talk to the man
But while 8,000 is an impressive number, in charge of it. Read on to discover how it
it’s not as impressive as 15,000. That’s all started, how Microsoft tried to torpedo
how many people the Munich city council it, and whether other cities in the world can
has switched from Windows to Linux over follow Munich’s lead…

52 www.linuxvoice.com
MUNICH FEATURE

Humble beginnings
Cast your mind back to 2001, and the state of Linux at
the time. It was well established as a server OS and
fairly well known among computing hobbyists, but still
a small fish in the desktop pond. Gnome and KDE
were still young whippersnappers, while hardware
detection needed improvements and top-quality
desktop applications were lacking in many areas.
So for an entire city council to even consider
moving to a largely unknown platform was a major
event. Still, it happened gradually, as Peter Hoffman,
the project leader for LiMux, told us in his office:
“Back in 2001, a member of the Munich city council
asked: are there any alternatives to using Microsoft
software? And based on that question, we put out a
tender for a study, which compared five platform
options. One was purely Microsoft-based, one was
Windows with OpenOffice, one was Linux with
OpenOffice, and so forth.”
As the study progressed, two main options
emerged as choices for the council: remaining with a
purely Microsoft solution, which would involve
upgrading existing Windows NT and 2000 systems to
Peter Hofmann is the
XP; and moving to a purely Linux and open source would foster the local IT market, as the city would pay
leader of the LiMux
alternative. “If you lay more emphasis on the local consultants and companies to do the work. project, and explained
monetary side, the pure Microsoft alternative would its ups-and-downs from
have won, or if you lay the emphasis on the strategic Ballmer marches in his office overlooking the
side, the open source alternative was better.” In May 2003, the city council was due to vote on Frauenkirche.
whether to make the big switch to Linux. But
Doing the maths Microsoft didn’t stand still: Steve Ballmer, the
That was interesting enough – that staying with infamously loud CEO, flew over to speak with Munich’s
Microsoft would have been cheaper. Given the cost of
buying licences for Windows and Office, you’d think
What is the LiMux Client?
that sticking with Microsoft would’ve cost far more
than switching to Linux. However, the calculations Put simply, it’s a customised version of it looks rather plain. A new version of the
were based on a five-year period, so they mostly Kubuntu. We had a chance to explore it in LiMux Client is due this year; it will be
Peter’s office, and it’s very much what you’d based on Kubuntu 12.04, an LTS (Long-Term
covered migration costs (staff, technical support,
expect from an older Kubuntu release: a Support) release. With this, LiMux users
retraining users etc.) rather than operational costs Start menu in the bottom-left, various office across the city will make the transition to
(buying new hardware, licence fees and so forth). But and productivity applications installed, KDE 4, and experience something rather
how did the LiMux team determine that Linux was a and a generic theme. There’s a bit of LiMux more polished than the KDE 3 desktop
better choice strategically? theming in the wallpaper, but otherwise they’ve been used to.
“With the Linux alternative, we saw that it would be
possible to implement the security guidelines we
wanted to have. At the time there was a lot of
discussion about Windows 2000 and the calling
home functionality. If you asked Microsoft at that
time, ‘which one of your programs are calling home?’,
they said ‘err, yeah, maybe some, or not’. So we didn’t
get a clear answer at that time, and we thought there
would be a great advantage from a security
perspective to using Linux.”
One of the biggest aims of LiMux was to make the
city more independent. Germany’s major centre-left
political party is the SPD, and its local Munich
politicians backed the idea of the city council
switching to Linux. They wanted to promote small and
medium-sized companies in the area, giving them
funding to improve the city’s IT infrastructure, instead It’s not pretty or bleeding-edge, but LiMux has done a fine job of replacing old
of sending the money overseas to a large American Windows NT and 2000 installations.
corporation. The SPD argued that moving to Linux

www.linuxvoice.com 53
FEATURE MUNICH

companies, Gonicus and Softcon, won the tender with
a solution based on Debian.”
Gonicus provided consultants, and the city council
recruited new technicians – eventually there was a
team of 13 working on the LiMux project. They started
creating a custom version of Debian and by 2006 the
roll-out was beginning. But the choice of Debian
caused them some minor headaches further down
the line:
“In 2008 we saw that Debian was clearly stable, a
good thing, but not the best if you want to use new
hardware. They are always a few years behind. We
also wanted to have a clear timetable for when new
versions would be available. In Debian, when it’s ready
it’s ready, so you can’t base a release plan on it. Those
two things were the basis for switching from Debian
to Kubuntu.”

From Debian to Kubuntu
Another reason for using Kubuntu was the KDE
This chart shows the
mayor, Christian Ude. But this had an adverse effect, desktop. It was clear to the LiMux team that some
migration path in 2012:
from 9,000 desktops at the as Peter explains: users would fight back against the change –
start of the year to 14,000 “Steve Ballmer tried to convince our mayor that it especially if they regarded the current system as good
by the end. would be a bad decision to switch to open source, enough, and the new one as something forced on
because it’s not something an administration can rely them by politicians. So KDE was chosen as it could
on. But some members of the city council said: what provide an interface very similar to that of Windows
are we, if one member of a big company simply comes NT and 2000, as used by the various departments of
here, and he thinks he can just switch our opinions?” the city at the time. How did people respond?
And it just got worse for Microsoft’s boss. “Our “There are different levels of users. Some would say:
mayor was preparing for a meeting with Steve ‘This button was green before, and it isn’t green now,
Ballmer, and because English is not his native so I cannot work like this!’ And the others say: ‘Just
language, he asked his interpreter: ‘What shall I say if I give me something, I have to work, and I’ll get used to
don’t have the right words?’ And the interpreter replied: it’. We had that kind of range of users, but most were
‘Stay calm, think and say: the first type.”

“LiMux has been a success, What else can you offer?’
Later on during the
Peter and his team worked to ease the migration
process by organising meetings and roadshows
and has shown how flexible meeting, our mayor was around the city where people could come and see

and effective Free Software is.”
quickly at the point Linux in action. They had Q&A sessions and even a
where he had nothing to Microsoft-free zone set up with Linux computers to
say to Ballmer, except for play with. The goal was that users would get a
‘What else can you offer?’ several times. Years later, he preview of what they’d be using a year or two down
heard that Ballmer was deeply impressed by how hard the line.
he was in negotiations!” “Some people came to us and said: ‘Can I use a
mouse? I thought Linux was only command line
Alea Jacta Est based’. One person came with a floppy disk and said
So Steve Ballmer flew back to Microsoft HQ, the ‘My most important documents are on this. Is it still
Munich city council voted, and it voted in favour of possible to work with them?’ So we showed that it
Linux. History had been made. GNU/Linux and Free was possible to open them on Linux. We were always
Software users around the world were pleasantly trying to give information to the users: what was
surprised by the decision – especially as it had been happening, and why it was happening.”
made in Munich and Bavaria, one of the more While LiMux was the central project in charge of the
conservative areas of Europe. Something big was operating system, the roll-out and migration was
going to happen, but it needed time to take root, as handled by individual departments. There was no
Peter explains: specific deadline: departments would choose by
“We could not to start the migration next day, but themselves when to handle the transition, and the
wanted to do a proof of concept first. In 2004, we LiMux team would provide the technical know-how to
started to take preliminary steps for the migration, and perform the migration.
one of them was to put out a tender for a Linux-based Not every public sector employee moved to Linux
solution. Ten companies approached us trying to sell though. Education was one area in which LiMux
their solutions, and a consortium of two small couldn’t get involved, because the decisions about

54 www.linuxvoice.com
MUNICH FEATURE

Who’s next?

Surprisingly, the success of LiMux hasn’t resulted in a flood
of similar projects across Europe, although we all know how
slow things move in politics. Peter has been talking to other
administrations around Germany – but whether anything
will come from them remains to be seen. A similar project,
Wienux, aimed to move the city of Vienna over to Linux, but
hit stumbling blocks in 2008.
Peter’s reasoning for this: Wienux didn’t have proper
political backing. You need more than just a couple of
technically minded councillors to make such a big project
a success – you need to know that you have the support of
the majority.
It all has to start somewhere, though, so maybe if we
all write to our local councillors, point out the success of
LiMux and ask them to consider a similar plan, there’ll be a
lot more FOSS in our towns and cities in 10 years’ time…

educational software are made at a national level in
Germany. In addition, a few systems with very esoteric
requirements are still running Windows, although
Peter tried Wine:
“We have a very limited Wine installation, because
there’s always the need to save the configuration of
Wine together with the application. They’re deeply
dependent. If you change the version of Wine, you
have to do something with the application, and
vice-versa. We saw that we’d have to use 10 or 15
different configurations of Wine on the same machine
in some cases.”
Some software vendors won’t support their
programs if they’re running on Wine rather than a
native Windows installation, so in the end the LiMux
team only deployed two Wine installations.
While the LiMux version of Kubuntu was fairly
standardised across the different departments in the
city, it took a lot of work to provide the same
functionality as the myriad Windows setups
previously out there. Peter and his team counted over
50 different configurations of Windows in use, so even
Yes, there are cuddly
when the transition had gone well for one department, with the migration to the Linux platform. Based on
penguins in the LiMux
the requirements of the next one were often those parameters, Linux has saved us €10m.” offices. All is good in the
completely different. A respectable sum indeed – but some companies world.
Today, the IT infrastructure is a lot more centralised, weren’t happy with it. HP compiled a study which
with the LiMux developers issuing new releases and concluded that no, actually, switching to Linux had
giving support. It’s much easier to fix problems and cost the city €60m. Had Munich stayed with Microsoft
help people when you have roughly the same and moved to Windows XP and Office 2003, it would
operating system on each PC, rather than non- only have cost €17m. What did Peter and his team
standard custom setups with different service packs, make of this?
patches and so forth. “We contacted HP and said: ‘Nice numbers, how did
you calculate them’? And they said ‘Uh, um, that was
Money talks an internal paper and not supposed to be published…’
While the initial aim of the project wasn’t to save They published a summary, but it was not clear for
money, it’s still what a lot of people talk about. Today, anyone to see how they calculated.”
over a decade down the line, has LiMux been a good As a major partner of Microsoft, it’s not surprising
idea in terms of finances? that HP would try to put a different spin on the project.
“Yes, it has, depending on the calculation. We did a But the proof is in the pudding: LiMux has been a
calculation and we made it publicly available on our success, has shown how flexible and effective free
information system for the city council. We have the software is, and will hopefully inspire many other cities
exact same parameters for staying with Windows as to follow its lead in the future.

www.linuxvoice.com 55
FEATURE YOUNG REWIRED STATE

Look inside the philanthropic project that’s
fostering the next generation of coders, with
Mayank Sharma.

O
pen data teaches you that you can make the Rewired State, at Google HQ in London with the
world a better place – not everything has to intention of introducing open data to kids under the
be closed up, and it’s nice to share things like age of 18.
that, as it can be interpreted in many ways, for many To her surprise, just three kids signed up for the free
things!” This sage advice doesn’t come from a veteran event! It took the organisers three months, and a huge
open data advocate, but rather from 14-year-old credit card bill for hotels and trains, to find students
George Streten. Streten is one of the hundreds of kids, from all over the UK to fill up the quota of 50 seats.
all under 18, who have received neural enhancement That experience gave Mulqueeny an unprecedented
at the Festival of Code event organised by Young insight into the ICT education in schools around the
Rewired State (YRS). UK. Students shared their frustrations of being let
“We are about finding those young programmers down by a curriculum that did not support technical
and bringing them together at open events around the skills or computer science and forced these
world introducing them to open data, and each other”, enterprising students to teach themselves.
explains Emma Mulqueeny, the founder of YRS. Rather than being disheartened, Mulqueeny
At the events, the kids collaborate with their peers resolved to give these self-taught kids, who had been
to build projects based on any of the various publicly programming in isolation, a platform on which they
available real-world open data sets. Mulqueeny is not could interact with like-minded peers. By 2010 she
just a vocal proponent of open data but also played a had quit her job and founded Rewired State, a
pivotal role in showcasing its potential to Government for-profit enterprise that organises hack days and has
officials, which eventually led to the birth of the UK a network of more than 1,000 software developers
government’s open data portal, data.gov.uk. and designers. YRS became a philanthropic arm of
While she was conducting hack days for the Rewired State, meaning that, unlike Rewired State,
government, Mulqueeny noticed that all the coders YRS is a non-profit social enterprise.
were older than 25 years of age. So in 2009, “a small
group of us decided that we needed to bring the open Festive season
government data revolution to the next generations”, YRS has been organising hackathons for kids ever
writes Mulqueeny on her blog. since. From a weekend-long session in 2009 the event
So in August 2009, she along with a bunch of is now a week-long affair, and the number of
friends, organised a weekend event, christened Young participating kids has been gradually rising.

56 www.linuxvoice.com
YOUNG REWIRED STATE FEATURE

Tyriah Taylor, 10
I kept asking my mum for The ﬁrst YRS event I went to was at the
a new 3DS and games Rutherford Appleton Laboratory [in Oxford]. I
for my Nintendo DSi and learnt some Python, and we made a game in
Wii. Eventually, my mum Game Maker called Food Fetcher. Last year
got annoyed and told I went to the Microsoft Campus in Reading
me that I could make my and I learnt some HTML, CSS and PHP. We
own games. She started made a website called Top Tweets, which is
looking for computer clubs and that is when a Twitter search engine, where you put in a
she found Young Rewired State. word or hashtag and it returns the top 3 most
I didn’t think it was going to be very retweeted and favourited tweets containing
interesting. However, right from when I that word/hashtag.
got there we had talks and tours of the We don’t have any workshops at my
venues. We had practice sessions for our school. We have Scratch, but I don’t think
presentations for the Festival Of Code, which anyone else knows how to use it, except me.
helped build our conﬁdence. Young Rewired I can’t wait for YRS 2014 and I am hoping
State is one of the best experiences I have that some of my friends will be coming along
Young Rewired State has grown from 50 participants in ever come across and it was great fun! as well.
2009 to over 1,000 today.

While YRS is involved in various activities to engage available on-site at each local centre and even online
with coding kids through the year, it brings young at the YRS IRC channel. The mentors assist the kids
coders together from across the UK once a year in a with their projects.
meeting called the Festival Of Code. This stretches From Monday to Thursday the young programmers
over a week, during which kids create all sorts of assemble at their centres and hack on their projects
coding projects. All the apps are built around open to create a functional prototype. On Friday, everyone
data -- from something as simple as a website to from across all centres
access data to apps that turn that data into
meaningful information.
travels to and
assembles at a central “YRS brings young coders
The event is held in the first full week of August of location in the UK to together once a year in an event
called the Festival Of Code.”
every calendar year. The event works by gathering present their work to a
kids at local centres all across the UK. At the centres, panel of judges.
the kids are encouraged to pair up with their peers, Until 2013, the
although they are free to work on their own as well. festival culminated in the Custard Factory in
They can create anything they want, using any Birmingham. This year that venue has shifted, and the
types of programs or equipment they’ve brought weekend will be held at the University of Plymouth.
along. The only requirement is that the project must Over the weekend, the young coders will present
include at least one open data set. Mentors are their projects to a panel of judges during the

George Straten, 14
I heard about Young Rewired State from
a friend. I hadn’t met him in person
before; we’d met on Twitter. He invited
me to write for his blog, and while
chatting to him on one of the numerous
Skype calls that we had, he mentioned it.
I don’t really know what I expected from
the event to be fair. If I’m honest, I expected it to be a little
dull, but throughout the week, my opinions couldn’t have
changed more dramatically… I really enjoyed the event!
We created a lost and found website, for the whole of the
UK. I created a 30-second video advertisement for it too. At
school, we never have any experiences like this. We don’t
ever have-IT based workshops, which is a huge shame, so it
was different from anything that I’d ever experienced.
Young Rewired State’s Festival of Code not only is an
amazing opportunity, but an opportunity to meet people.
I’ve met a huge community of amazing people, which I’ve
stayed part of through various social media platforms, such
as Twitter – without YRS, I would never have met such
talented people. Once I’m over 18, the maximum age limit
to attend as a participant, I hope to join Young Rewired
State, and help other people like me to engage with others
and share their talents.

www.linuxvoice.com 57
FEATURE YOUNG REWIRED STATE

tested in the UK. The events are currently restricted to
a weekend, just like the first YRS event in 2009. It’ll
then be extended to a whole week and stretched to
multiple centres across the new country.
The first YRS Everywhere event was held in 2013 in
New York in collaboration with a number of networks
such as Mozilla Hive and the Museum of the Moving
Image in New York.
Just like the first-ever YRS event in 2009 in the UK,
the event in New York also invited 50 kids for a
two-day hackfest. During the event they worked with
open data local to the US and came up with projects
that were of local interest. The kids programmed
under the guidance of local developers as well as
YRS’s worldwide mentor network.
The event in New York was followed by a similar
two-day hackfest in Berlin, again with the help of
Emma Mulqueeny, Young well-known local networks such as SAP and the Open
Rewired State’s founder,
Knowledge Foundation. Just before the close of the
has in the absence of
year, the team went back to the USA, this time for an
government policy been
preparing kids for the event in San Francisco. In 2014, the network is
future since 2009. planning a YRS Everywhere event in Asia in Singapore.
The YRS Everywhere events follow the same
pattern as the Festival of Code. On the first day the
participants form groups and choose the open data
preliminary heats and the semi-final rounds that will set that they will work on. They work on their projects
be held on Saturday, and the finale on the Sunday. till the afternoon of the next day. In the evenings the
Their friends and family members are welcome to hacks are presented to the panel of judges.
attend and watch over the proceedings. You don’t have to be an ace coder to participate in a
YRS event. In fact, according to the YRS website, the
Going global
In five years, YRS has grown from a single weekend
event with 50 young coders to a week-long event
across the UK. Now Mulqueeny and the YRS team are
reaching outside the UK in order to foster young
programmers in other countries.
The YRS International events are held under the
banner of the YRS Everywhere program. The idea with
YRS Everywhere is to replicate the scale that has been

Planning a YRS event
Organising an event that runs simultaneously pointing to her website, which details the
all across the country and involves over a requirements for a centre. They also have
thousand kids is no small feat. But Emma a team that check the credentials of the
Mulqueeny and her small team manage to registered mentors. “We do not provide
pull it with relative ease. So we asked her: training for them, but we connect mentors
What does it take to organise a YRS event? from previous events with new mentors so
“Crikey, a lifetime!”, exclaimed Mulqueeny. that they can ask any questions they have.”
“As with running any hack weekend, the Beyond their main event, Mulqueeny says
practicalities are about venue, Wi-Fi and that the YRS Everywhere events are relatively
power,” she explains. Once that’s taken care simple to setup. “The organisers apply and
they focus on “who and how to recruit” we check their credentials: have they run
which applies to both the participating kids hack weekends before, do they have access
and their mentors. Next up is selecting the to a developer network versed in Open Data
panel of judges and the prizes. An important to act as mentors, and so on.”
aspect of any YRS event is access to local If the organisers meet these criteria,
open data. Mulqueeny says it “is critical, as Mulqueeny and her team guide them to
we try to make this about local challenges.” ﬁnd the young participants, based on their
“For the Festival of Code, centrally we deal experience, and support them remotely. If
with all of the logistics and fundraising, but required, the organisers can pay them to put
centres act as our outposts,” she continues, together a team to help run the event. These kids aren’t just learning a new skill; they’re sharing,
and learning from each other.

58 www.linuxvoice.com
YOUNG REWIRED STATE FEATURE

youngest participant in the 2013 edition of Festival of
Code was a mere five years old!
If you have basic programming skills, you are good
enough to be a part of YRS. The group accepts coders
of all levels; however, it helps if you at least have a very
basic understanding of HTML. There are no lessons in
programming dispensed at the Festival of Code event.
Instead, the event helps young people learn from and
teach each other.

Low barrier to entry
According to an FAQ on its website “The only thing we
ask is that when you come along you get involved and
use your skills to the best of your ability, and we
encourage you to be adventurous in your learning.”
To encourage more participation YRS has
introduced the Google Assemblies program in
partnership with Google. The idea behind the program
is to introduce kids to YRS and coding.
During a Google Assembly, a YRS participant gives
Young Rewired State isn’t
an assembly presentation at their school. They are
about coding for the sake
assisted by YRS mentors to prepare for the of it: the emphasis is on
presentation using slide decks, videos and YRS and using open data to improve
Google swag. participants local areas.
With these assemblies, YRS intends to connect with
young students via one of their peers who can share
their experience about the event and encourage
participation with their enthusiasm. They are hopeful
that the association with Google will help demonstrate
how important their talents are to a multinational Code event has come to an end. The Hyperlocal
marquee brand that everyone can connect with. program is designed to ensure that the prototypes
designed during the week complete the journey to a
Pitch in! finished product.
According to Thom Brooks of YRS, organising the The Hyperlocal centres will run sessions where the
2014 edition of the Festival of Code will cost them kids can come back to work on their projects under
around £250,000. That’s quite a sum to raise, and the guidance of their mentors. The YRS team will help
being a non-profit organisation they rely on prepare the centre to run sessions as per the schedule
sponsorship from individuals and institutions. that suits the centre.
If you appreciate the work of Young Rewired State If you have programming skills but are over 18 and
and wish to donate, you can email Emma Mulqueeny can’t participate in the events as a coder, you can lend
at emma@rewiredstate.org for the official channels your skills and expertise and volunteer as a mentor.
of donation. The idea behind all YRS events, including YRS has a thriving mentor community. Traditionally
the Festival of Code, isn’t to make any profit. All the mentors for the

“If you’re over 18 and have
funds received are used towards organising the YRS events have
festival itself as well as for the fund to support families been drawn from
who can’t spare the monetary resources required to the Rewired State
programming skills you can lend
your experience as a mentor.”
cover the associated travel costs. network, but that
Besides direct monetary help there are several other requirement has
ways you can help the initiative. If you have a large been relaxed with
room or a conference hall that you can spare for a their growing popularity.
week, you can sign up with YRS as a Festival of Code If you fancy getting involved, the YRS website has
Centre. You’ll also have to assign an individual who loads of information on what it expects from a
will be the centre lead. When you register as a centre, mentor. Mentors don’t necessarily have to be
YRS will work with you to make sure you’re all set up physically present at a centre and can even guide the
well in advance. You’ll be listed on their website and coders remotely from anywhere in the world. YRS is
participants will be assigned to you based on their growing both within and outside the UK. After
geographic proximity. establishing a model for scaling the hackfest, the
You can also register your centre as a Hyperlocal team is replicating it in other parts of the world,
Centre. Such a centre allows participants to continue encouraging kids to solve their local civic problems
working on their prototypes even after the Festival of with open data and open source code.

www.linuxvoice.com 59
FAQ DOCKER

DOCKER
The ultimate deployment tool, or just another tech fad?

BEN EVERARD
However, you can have many copies of
everything else. Containers are a way of
independent OSes, but it all runs atop
the same kernel.
encapsulating this ‘everything else’ so There are advantages and
Ok, let’s start with an easy that they can share a kernel, and this disadvantages to this. Because they
one: what is Docker? enables you to run multiple distros on run the same kernel, you can’t run
That’s simple: it’s a tool set for the same hardware. different operating systems like you can
managing deployments of with virtualisation. However, on the
containers. Like having a dual-booting other hand, because they don’t simulate
Linux system? the CPU, the performance is better.
You’re stretching the definition No. Using containers, you can run
of ‘simple’ a bit. Can you break multiple distros at the same time, Great! Now I understand it, and
it down for me a bit more? Let’s start or, as is more common, using the same we’ve still got a page to go.
by explaining what a container is. distro multiple times. Shall we just stick a picture of Linus
OK. Remember that Linux is just Torvalds in there and nip off to the
the kernel and the operating Ah, so containers are a form of pub early?
system is this plus all the tools that sit virtualisation, like Virtualbox Not so fast! That’s containers. We
on top of it? or Qemu? need to get onto Docker itself.
From a user’s perspective they’re
Yes, but I thought I got to ask pretty similar. You have a host Oh right, yes. You said before
the questions? OS, and within that host OS, you can that it’s a tool set for
Sorry. A mild digression only. The boot more versions of Linux. However, managing deployments on
Linux kernel is the bit that sits on at a technical level, they work in very containers. I know what containers
top of the hardware and controls different ways. In virtualisation, you are, but why would you want to
access to the CPU, memory, and all the have an application on the host OS that deploy them anywhere?
other stuff that makes up your simulates a CPU, then you have another The big advantage of containers
computer. Normally, you can only use entire OS (including kernel) that runs on is that you can encapsulate an
one kernel on a computer at a time. this simulated CPU. entire environment into a single block.
In containers, you only ever have one This enables developers to pull all the
kernel. It’s the same for the host libraries, data, and software into a
“You could have a Docker operating system and the other
operating systems that you run. The
single container and distribute this. By
sending the container, rather than just
image for OwnCloud and containers have their own chunk of the the software, it means they don’t need
another for WordPress.” filesystem where they keep all their
data, and behave exactly like
to worry about dependencies, different
configurations, or anything like that.

60 www.linuxvoice.com
DOCKER FAQ

So it’s a bit like statically
compiling software, but
including the whole OS?
I’d never thought of it like that, but
I suppose it is really.

Sounds awesome! What’s the
inevitable downside?
Nothing major, but the containers
will take up more disk space than
just the plain software, and they have to
be updated separately to keep them
current with the latest bugfixes and
security patches.

So is Docker poised to become
a universal replacement for
apt-get, Yum, and all the other
package managers? You can get a taste for Docker without the hassle of installing anything by trying out the project’s
Not really. No one’s suggesting interactive tutorial at www.docker.io/gettingstarted.
that containers are a sensible
way of installing all your regular The main tool is (unsurprisingly) just one year old (happy Birthday
software. The main target market for called docker, and it has options Docker!). In that time it’s come all the
Docker is people providing services for getting and manipulating containers. way to version 0.9. The earliest plan we
across a network. For example, you There’s a repository of containers that heard about was for a release of
could have a Docker image for have been made for common purposes. version 1.0 in October 2013, but by
OwnCloud, and another for WordPress. You can grab these with: November that year, it had been pushed
They would each have their own docker pull <name> back to February 2014. At the time of
environments with everything installed, Then, once you’ve got one installed, you writing, there was still no sign of it, but
set up, and ready to run. can run commands on it with: we don’t expect it to be much longer.
By keeping everything contained in docker run <image-name> <command> Of course, just because it’s called
this way, it’s really easy to customise That’s the basic use. There are also a version 1.0 and the team behind it say
and deploy. A developer could pull the few options to help you manage the that it’s production-ready doesn’t mean
Docker image to his or her development containers. It’s complex technology, but it’s ready for everyone. Sysadmins are a
machine, make any changes they like, it’s surprisingly easy to use. conservative species by nature, so we
then push it to the server. They don’t don’t expect many people to start using
need to worry about the development This all sounds so good, you it in important services for a while yet.
environment being different to the live must have found it really
environment, because the whole useful when setting up the Linux I’m not a conservative
environment is included in the container. Voice web services. sysadmin, I’m a reckless
It it doesn’t matter if it’s developed on Actually, no. We didn’t use maverick programmer. How can I get
bleeding-edge Arch Linux, and deployed Docker. It is, as you say, really started with Docker?
on ultra-stable Centos, it will always run good, but it’s also really new and still You won’t find it in many distros’
the same. As well as making it easy to under heavy development. The current repositories just yet, but there are
develop, this should remove much of version is 0.8, and the people behind it packages for it for most major Linux
the hassle of setting up test servers, or recommend that you don’t use it for distributions at http://docs.docker.io/
migrating to a new environment. production systems until version 1.0 at en/latest/installation.
The developer can also make any least. It’s not unstable, but it’s not yet as
changes they need to the environment mature as we like our server software You said it ran on Linux
without worrying about how these may to be. Of course, some people are using containers. I have this friend
affect other software running on the it on production machines. We’re just a who runs a commercial OS and won’t
server, because that software will be in little conservative about such things. listen to reason. Can he run it?
a separate container. Sort of. You can run Linux on
Ah… so I should expect it about OS X or Windows in VirtualBox,
I almost understand your first the same time GNU/Hurd is then run Docker in this. There are
point now: ‘a tool set for ready? Perhaps in time for Linux instructions at the installation website
managing deployments of Voice #100 (or Hurd Voice #1). above. Of course, it’s far better just to
containers’. What sort of tools are Less of your cheek! The first give your friend a talking to about the
typically in the set? release was in March 2013, so it’s advantages of open source systems.

www.linuxvoice.com 61
SYSADMIN

SYSADMIN
System administration technologies brought to you from the coalface of Linux.

Jonathan Roberts
dropped out of an MA
in Theology to work
Linux containers
with Linux. A Fedora Enterprise-grade virtualisation on a real kernel.
advocate and systems

W
administrator, we hear
hile Linux containers have been administrators to group processes, and all
his calming tones
whenever we’re stuck around for a while, they’ve their future children, into hierarchical groups.
with something hard. recently been gaining more Various subsystems can then be used to
recognition as a lightweight alternative to strictly manage the processes and the
When new products are being developed, traditional virtualisation products like KVM resources they interact with.
one of the most important choices to be or VMWare. With the arrival of LXC, Docker,
made is which technologies you’re going
and the next generation of distributions, Control groups
to build on top of. Obviously, the right tool
we’re all likely to see a lot more of them over If you have systemd installed, you can
for the job is the correct answer, but how
you decide which tool is the right one is the coming decade. quickly inspect what cgroup your processes
less obvious. As with all virtualisation, the idea of are running in with the ps command:
As a sysadmin, my goal is to ensure that containers is to make it easy to run multiple ps -aeo pid,cgroup,command
our technologies are the most secure, the applications on a single host, all the while Running this, you should see that all
most stable and the most familiar. All of ensuring each remains separate. This processes are running in cgroups that exist
these characteristics will reduce the enables the administrator to carefully in a hierarchy below the systemd cgroup.
chances of me being woken early in the manage the resources assigned to each You could use systemd unit files to manage
morning, and when I am inevitably woken application and to ensure that they can’t the resources assigned to a service (indeed,
in the morning, I’ll at least have the interfere with each other. if you’re using systemd, this is probably the
knowledge and experience to have half a
What makes containers different to best way to use cgroups), as described in
chance of fixing whatever went wrong.
traditional products is that they don’t do any the last issue, but you can also interact with
For developers, however, operational
requirements often seem restrictive. hardware emulation. Instead, the cgroups directly, too.
Enterprise distributions come with applications in question all run directly on There are a collection of tools available in
technology that’s more than three years top of the host kernel, just like any other the libcgroup-tools package, including
old and requires the developers to write process. Separation between the running cgcreate, for example. You can use this tool
far more lines of code. This means there’ll containers is achieved through the careful to create a new cgroup as follows:
be more bugs and they may well take use of a number of Linux kernel features. cgcreate -g memory,cpu:mysql
much longer to get the product to market. Control Groups (cgroups) are the first of This will create a new cgroup called mysql
During the two years I’ve worked as a these features, and are probably the best which has been tied to the memory and cpu
system administrator, I’ve seen this known. They provide a means for subsystems. You can then take advantage
conflict crop up several times, but never
seen any obvious solutions that make
both parties happy. I agree with the
‘DevOps’ crowd, who argue that part of the
solution is to ‘better align incentives’,
making operations more responsible for
delivering software and developers more
responsible for maintaining it.
We also need improvements from
distributions, providing more reliable
means for getting recent, but stable,
software packages on to well tested
platforms. The Fedora.next wheeze may
be going some way to address this, as do
PPAs in Ubuntu. Hopefully we’ll see this
mentality begin to translate to Debian and
RHEL in the coming years, too.
The highlighted area shows the cgroup in which the different processes are running. As you can
see, all are either in the systemd defaults of systemd:/user.slice and systemd:/system.slice.

62 www.linuxvoice.com
SYSADMIN

of a command, such as cgset, or interact
directly with the virtual filesystem exposed
by cgroups, to manipulate the resource
limits of this newly created group:
cgset -r swappiness=xxx /sys/fs/cgroups/memory/
mysql
This command will set the swappiness
parameter of all processes running in the
mysql cgroup to xxx. To add a process to
the cgroup, all you need to do is echo its PID
to the tasks file in the cgroup’s filesystem or
use the cgclassify command.

Namespace isolation
Namespace isolation is the other key
technology that makes containers possible
on Linux. Each namespace wraps a
particular system resource, and makes The output of this long listing in the /sys/fs/cgroup directory shows all the different subsystems
processes running inside that namespace that are available for managing processes with cgroups on a default Fedora 20 installation.
believe they have their own instance of that
resource. There are six namespaces in Linux: install the lxc package on Ubuntu and lxc.cgroup.cpu.shares = 1234 Sets the
mount Isolates the filesystems visible to a Fedora, but in the case of the latter, you share of CPU that the container has.
group of processes, similar to the chroot should also install lxc-templates and lxc.utsname = linux-voice Sets the
command. lxc-extras for a better experience. hostname of the container.
UTS Isolates host and domain names so Once that’s done, creating a new container, lxc.mount.entry = /lib /home/jon/
that each namespace can have its own. depending on your requirements, can be containers/busybox/lib Specifies directories
IPC Isolates System V and POSIX simple. In the /usr/share/lxc/templates on the host filesystem that should be
message queue interprocess directory, you’ll find a collection of scripts mounted in the container.
communication channels. that will create some default containers, This configuration file means you can
PID Lets processes in different PID including Debian, Fedora and Ubuntu system apply the existing templates in quite flexible
namespaces have the same PID. This is containers, and sshd, BusyBox and Alpine ways, but if you really want to create a
useful in containers, as it lets each container application containers. To put one of these to custom container, you’re going to have to set
have its own init (PID 1) and allows for easy use, all you need to do is run lxc-create: to work creating your own template script.
migration between systems.
network Enables each network
namespace to have its own view of the “Creating a Linux container is paradoxically easier
network stack, including network devices, IP than creating an application container.”
addresses, routing tables etc.
user Allows a process to have a different lxc-create -n linux-voice -t /usr/share/lxc/templates/ As the LXC man page says, creating a
UID and GID inside a namespace to what it busybox --dir /home/jon/containers/linux-voice system container is paradoxically easier
has outside. -n sets the name of the container. than creating an application container. In the
A quick way to experiment with -t says which template you want to use. latter case, you have to start by figuring out
namespaces yourself is to use the unshare --dir says where you want the rootfs for which resources you want to isolate from
command. This will run a particular the new container to be created. the rest of the system, and then figure out
program, removing its connection to a This command creates a directory in how to populate the appropriate parts of the
particular namespace of its parent: /var/lib/lxc with the name set by the -n flag. file system etc. In the former case, you
sudo unshare -u /bin/bash The contents of this directory are populated simply isolate everything – much simpler.
This will create a new bash process that by the script specified with the -t flag. If you Once you’ve created your container with
doesn’t share its parent UTS namespace. If look at, say, the BusyBox template, you’ll see lxc-create and modified the config file as
you now set the hostname to foo, you’ll then that this script sets up a filesystem you see fit, you can start it with the lxc-start
be able to look, in another shell on the same hierarchy, copies appropriate binaries and command, use lxc-console to get a console
system, and see that the hostname in the installs important pieces of configuration in it, and shut it down with lxc-shutdown.
root (original) namespace hasn’t changed. with heredoc statements. While cgroups and namespaces have
Inside the created directory, you’ll also find reached a degree of maturity in Linux, the
Linux containers that a config file has been created. This user experience still has some room for
Now that you have an idea of what the defines which system resources are to be improvement. If you found the lxc-
underlying technologies do, let’s take a look isolated and controlled by the container. The commands tricky to use, you might want to
at Linux Containers (LXC), a userspace man lxc.conf command goes in to detail on install libvirt-sandbox, which will provide a
interface that brings them together. To what options can be put in this file, but a few set of scripts and extensions for using LXC
install the LXC userspace tools, you need to key examples will be helpful: through the familiar libvirt tools.

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CLOUDADMIN

CLOUDADMIN
Nick Veitch opens your eyes to the technology behind the cloud server revolution.

Jenkins
Testing code yourself? Why not get a minion to do that for you?

W
ouldn’t it be great if things worked The name sounds like some sort of
all the time? I mean, software maths purgatory. Continuous integration
things, not people things. Gosh, was born out of the age that gave us agile
the world would be a better place if I worked programming. The idea is pretty good, and
hardly at all. That’s why software was all but indispensable in the modern world
invented isn’t it? of group coding on complex software
But things (including me) do not work all properties. Commits made by coder #1
the time. In fact, in the world of software may be all well and good, and coder #2 is
development, particularly in the new world well known for being cautious and testing
we now call devops, things are almost everything, but if they both land changes,
perpetually operating in a mode of non- perhaps the two new parts don’t interact as
functionality. What is very useful to know is they should?
when, almost miraculously, there is a small Breaking code is usually ridiculously easy,
window of time when software works as it is even with parts that seem to be backwardly If you are bored with butlers, you could always
replace the Jenkins logo with Chuck Norris.
expected to. In a smart, switched-on world, compatible – it is often the difference
we can capture this moment so we can between the programmers’ perception of
work out what went wrong/right. This is the how a particular block of code works, and on. The basic principle is that you submit a
world of continuous integration. how it actually works, that leads to ripples of job (maybe triggered automatically by time,
wrongness in the edge cases. or by a merge to a public repository) of code.
Testing is therefore a good thing, and Jenkins then spins up a clean environment
continuous integration is a blessing. for the code to work in, executes your tests
and spits out a report. Actually, that is pretty
At your services much the least it will do. With an active and
In the early days of Agile, one system rose productive community, Jenkins has grown
head and shoulders above the others. Its a legion of plugins to automate everything
name was Hudson. Hudson was originally a from audit trails to uploaders for zubheim
Sun project, but with the acquisition of Sun (it’s a mobile app testing platform). There is
assets by Oracle (remember them), there a list of plugins so long I couldn’t possibly
were, erm, tensions. The project decided to read them all without more gin than is
rename itself ‘Jenkins’. Oracle went off in a medically advisable.
huff and took its newly trademarked name The only major downside to Jenkins is
with it. Hudson still exists, but we’ll leave you that it requires a bit of effort to get it working
to decide who came off best from that spat. the way you want. Though it was originally
Anyhow, the open source Jenkins project imagined as a Java testing tool, Jenkins now
became the de facto required tool for those covers an impressive range of languages
seeking CI nirvana. and additional functionality, but almost all
Jenkins itself is a behemothic Java app of these require adding plugins and some
(aren’t they all) which requires a server to run amount of configuration. The results of a

One of the Jenkins plugins can automatically
“Though it was originally imagined as a Java
control lights to demonstrate build status testing tool, Jenkins now covers an impressive
(picture by Dushan Hanuska).
range of languages and additional functionality.”

64 www.linuxvoice.com
CLOUDADMIN

that’s its primary purpose. And instead of
editing acres of config files, you can set up CloudBees
everything that travis can do in a simple file Cloudbees is a hosted service that offers
called travis.yml and add it to your github free Jenkins capabilities, so you can get
repository. Register with the Travis website pretty much everything you ever wanted
(sign in with your github credentials, flick a out of Jenkins, but without having to go
few switches to turn your repositories on through the rigmarole of running your
and Travis will do the rest. Every time you own service. The cloudbees people should
push updates to the repository, Travis will know what they are doing too – the CTO is
notice and add your jobs to the end of the Kohsuke Kawaguchi, the original founder
Log on to the Travis website and you can see of the Jenkins project.
the build queue and check out the console queue. Log in to the website and you can
output from your jobs. If only to find out what check the queue and see the console output
an idiot you are. of your jobs when they run. But there’s no
need, because Travis will send you plenty of
well configured, well honed system are very mails as well, telling you when builds have
worth it though (you should definitely try succeeded or failed, and helpfully giving you
the Chuck Norris plugin, which replaces the plenty of version info.
butler image on your reports with a random If you really want to know how easy it is to
image of a culturally significant martial arts configure Travis, here are a few examples; All the Jenkins service but without the
practitioner). As well as merely testing the firstly, a simple python project: trouble of having one of your own.
build and functionality of your software, language: python
you can automate all sorts of other tasks # versions of python to use
like publishing documentation or building python: anything. For a C project, the Travis file can
different versions. If you ever have the need - “3.3” be as simple as:
to build hierarchical projects, there is really - “2.7” language: c
nowhere else to start. - “2.6” That’s because Travis assumes you are
# command to install dependencies, e.g. pip install -r using Automake and will default to running
Did anyone prophesise these people? requirements.txt --use-mirrors ./configure && make && make test, so you
Due to the nature of its flexibility and all the install: can put any magic in your Makefile. There
gubbins that can be bolted onto it, you may - “pip install markdown” is no real dependency management for C
find it takes quite a while to set Jenkins up - “pip install configobj” projects, but that doesn’t stop you from
in a working fashion. For people who don’t # command to run tests, e.g. python setup.py test using the install section (or before_install:,
want to spend half their working day writing script: python mdconverter.py to run first) to fetch such things as you
new configs for Jenkins, there is Travis. This example declares the language, might need. You are also not limited to using
Travis is quite a bit simpler, but no less optionally selects a few different versions GNU make. For example, to use cmake you
capable. Part of this simplicity is due to the (they will execute as separate jobs) and would just need to add something like :
fact that you don’t have to set up a server has the install command to add any before_script:
to run Travis for you; it is a hosted service. dependencies. The pip tool is used in this - mkdir build
Actually, you can very much download the case to install any additional modules - cd build
open source code for Travis from github, but required by the Python file. - cmake ..
why go to the trouble of building your own The final line is the script to run. In this script: make
service (the docs don’t really give you any case, as our project is a simple linear Currently the Travis CI environment is an
help on this either) when the hosted service conversion tool, we just execute that, but image of 64-bit Ubuntu 12.04, so you can do
is free for open source projects. Travis you could run a separate script to do a pretty much whatever you need to with it.
integrates really well with github. In fact, number of tests, pass special parameters or If you have an open source project on
github and want a free, no fuss service,
Travis could fit the bill. Jenkins is better at
The Travis build matrix view gives you
all-round automation – if you need to do
a nice overview of your status , but I
think I would rather have a lava lamp. more than just build a project and run a
script, it is infinitely more powerful (with the
configuration headaches to match). But
whatever you choose, make sure you write
good tests! Continuous Integration as a
discipline means nothing if your tests don’t
make sure that things are working. Good
tests don’t end at “well, it compiled OK”, but
actually running meaningful tests with the
running code itself. Your code (and users)
will thank you for it.

www.linuxvoice.com 65
FOSSPICKS

Drukkar p66 Android-x86 4.4 RC p67 HotShots p68 rCSSmin p68 Gipfel p69
Lynx p69 Flpsed p70 Lynis p68 NightmareTris p70 Zatacka p71

FOSSpicks Sparkling gems and new
releases from the world of
Free and Open Source Software

Mike Saunders has spent a decade mining the internet for open
source treasures. Here’s the result of his latest haul…
Lightweight blog platform

Drukkar 2.0
http://drukkar.sourceforge.net

S
ituation: you want to set up entries as simple XML files, and is
your own blog. Options: a designed with minimum bandwidth
million and one competing overheads, so the “content should
blog platforms, each one trying to account for most of your web
be more feature-rich, flashy and traffic” as the developer puts it.
Web 4.0 than the last. End result:
you get tired of trying to work out Nice and simple
what’s right for you, give up, and go To install Drukkar, extract its .zip
to the pub instead. file directly into a location on your
Sounds familiar? Most of us web server (note that it won’t create
don’t need whizz-bang WordPress a subdirectory during extraction).
installations with all the trimmings Then edit config.xml and set
for our day-to-day musings, and the base_url and base_location
Drukkar does a splendid job with settings to match your installation
minimal requirements. It doesn’t path. Finally, make sure that the
need a database or special Apache entries, files and cache directories Drukkar’s default theme, “flat”, is clean and simple. To change the
modules or anything like that – its are writable by your web server text on the right, edit inc/sidebar.php.
only requirement is a web server account (eg www-data on Debian/
with PHP. Drukkar stores blog Ubuntu systems). Now access the Drukkar
installation in your web browser,
and voilà: your blog is ready to go.
You can see that a sample entry
has been created automatically. To
add new entries, go to edit.php in
your Drukkar installation and enter
the admin password (by default it’s
just password). You can then add a
new blog entry in plain text, HTML
or Markdown. It’s possible to add
tags to entries for organising them
later, and add files to them as well
(go to files.php to manage them).
See config.xml for more options,
such as changing the blog’s title
and creating a new password. It’s
all charmingly simple, lightning fast
and no-nonsense – we’ve got it
The official webpage of Drukkar is made in, you guessed it, Drukkar – a good old running for a tech-shy relative who
open source “eating your own dogfood” approach. wants his own type-and-go blog.

66 www.linuxvoice.com
FOSSPICKS

Operating system

Android-x86 4.4 RC
www.android-x86.org

Y
es, you can run the world’s Wi-Fi networks; Android will use the
most popular mobile emulated network adaptor. Also, if
operating system on your you can’t see the mouse pointer, try
desktop PC. And no, there are no disabling mouse integration from
pressing reasons to do so, other the VirtualBox menu.
than out of curiosity. But that’s why From here, it’s very much
we love Linux and Free Software, standard Android: the black bar at
right? If you’re absolutely bursting the bottom of the screen is almost
to do some Android development always present, and includes three
but can’t get your mitts on an buttons. The first takes you back to
Android-powered smartphone or the previous screen (useful if you’ve
tablet, this project might help you dived into several levels of settings),
out somewhat. Bearing in mind that while the second takes you back to
Android was developed specifically the home screen from whatever
for handheld devices, don’t expect app you’re using. The third button
to be amazed with this PC port. brings up a simple task manager The usual gamut
Still, it’s surprisingly usable. for switching between apps. of Android apps is included by default: its fonts are
Android-x86 is available from the bundled, along with a ridiculously tiny, so click the
project website (and on the Linux Our new Google overlords terminal emulator. three-dot icon in the top-right
Voice DVD) as an ISO image that Click the circle button with six dots (Android’s stock button for settings),
you can burn to a CD-R, or inside to view the included go to Preferences, and finally Font
alternatively, boot in VirtualBox. If software. Android-x86 bundles Size. When you’ve selected
you do the latter, make sure that Google’s apps, so you can something better (eg 16pt), click the
you provide at least 32MB of video immediately use Google+, Google back arrow in the bottom bar.
RAM to the VM, and choose Maps and other services without Android as a PC OS is little more
SoundBlaster 16 for the emulated extra fiddling. The Play Store is also than a novelty at this stage, but in
sound card. Boot from the ISO provided as well. We’re pleased to time it might be a useful desktop
image and at the initial menu, hit see that a terminal emulator is OS for non-technical users who are
Enter on the first entry to start the already familiar with its interface on
OS in live mode, running straight
from the disc. You’ll be asked a few
“In time Android might be a useful a smartphone or tablet. If we ever
had the time to do our podcast
questions before reaching the home desktop OS for users who are challenges, “use Android-x86 as our
screen. If you’re running VirtualBox,
you can skip the question about
already familiar with its interface.” sole desktop OS for a week” would
be a darn good ’un…

How it works: install Android-x86 to your hard drive

1 Boot 2 Partition 3 Install
Burn the ISO image to a CD-R – you’ll find it Choose a partition on your drive for the Choose ext3 as the file format, choose to
on this mont’s cover DVD – and boot from it. At the Android files. (This will wipe the data!) If you need to install Grub, and the files will be copied over.
initial menu, select the 4th option: Installation. partition manually, the third option runs cfdisk. Reboot and enjoy exploring the OS.

www.linuxvoice.com 67
FOSSPICKS

Screenshot creator/editor

HotShots 2.1.0
http://sourceforge.net/projects/hotshots

I
t’s something of a cliché to say full details. Once you have it
“Foo is like Bar on steroids”, but installed, enter hotshots and the
that certainly applies here. main window will pop up. The app
HotShots is a screenshot creation also drops an icon in your
and editing tool with nigh-on every notification area, so you can easily
feature you can imagine rolled in, pop it up when needed.
and it does a sterling job. You might
think: what’s so special about taking Many, many extras
a screenshot? Just hit the Print In the main window, the most
Screen key. Well, that’s fine if you important widget is Capture Mode.
HotShots lets you draw
just want a rather generic capture of Along with grabbing the whole writing documentation and want to
areas on the screen to
the screen, but if you want to add screen or a specific region, this also take as a screenshot, explain parts of an interface.
effects or annotations, it’s better to lets you save hand-drawn regions with the background set You can save your work as a .hot
use a specialist tool. with smoothed edges – something as transparent. file for later editing (eg if you want
HotShots uses Qt4 for its we haven’t seen in other screenshot to reposition elements), or export it
interface, and the dependencies creation tools. Click the fire button in PNG, BMP, GIF and other formats.
you’ll need on Debian/Ubuntu- on the left, and after you’ve chosen It’s even possible to upload
based systems are qt4-qmake, the area to grab, the editor will pop screenshots to an FTP server or
libqt4-dev, libxtq-dev and libxfixes- up. This is a mightily powerful tool image hosting site like Imgur with a
dev. Its installation process that lets you add snazzy-looking single click – great if you need to
includes several alternative shapes, arrows, numbered tags and quickly show someone else on the
methods – see INSTALL.txt for the text boxes; very useful if you’re net your current screen state.

CSS compressor

rCSSmin 1.0.3
http://opensource.perlig.de/rcssmin

I
f you’re developing a website, than you do, though. It simply strips
it’s all too easy to focus on out spaces, comments, semi-
home or office users with fast colons (where possible) and other
connections and unlimited bits and bobs that aren’t required.
bandwidth. But there’s an Two versions are provided: one is
increasing number of people on written in Python, takes its input via
expensive mobile data tariffs, and stdin, and spits the results to
there are still some people stuck on stdout. So if you have a file called
dial-up, so it’s important to consider style.css, compress it like this:
Before and after: our
all types of users and reduce your cat style.css | ./rcssmin.py > new.css 70k to 40k. This isn’t a world-
70k CSS file in the left-
site’s overall data requirements. Have a look in new.css, and you’ll hand window, and its quaking change, but if you’re
rCSSmin helps in this process by see that it’s not as readable as 40k crunched version on running a big website serving up
crunching your CSS files to the bare before, but considerably smaller. the right. hundreds of thousands of CSS files
essentials. Chances are that your We tested it with a CSS file from the every day, it all adds up and saves
CSS contains lots of whitespace Linux Voice Forums, and rCSSmin you bandwidth costs too.
and comments to make it easy to managed to shrink it down from The C version is designed with
read and edit, but the web browser performance in mind (it’s up to 50

“It’s important to reduce your
doesn’t care about that – it just times faster than the Python one),
wants the information. rCSSmin so you can even use it at runtime
doesn’t pull any fancy tricks or
pretend it knows your CSS better
site’s overall data requirements.” on your sites (ie crunching CSS on
the fly as it’s served up).

68 www.linuxvoice.com
FOSSPICKS

Mountain finder

Gipfel 0.4.0
www.ecademix.com/JohannesHofmann/gipfel.html

S
o you’ve had a lovely holiday where you can identify two of them,
in the Alps, and taken plenty but the rest are unknown to you.
of photos. Back home, you With the picture open, click File >
load up the pictures on your Linux Choose Viewpoint and select the
box and start browsing them. “Aha”, name of a mountain that you know
you say, “there’s the Zugspitze, is in the picture. (The database is
Germany’s highest mountain. But extensive but some of the names
what’s that one behind it?” With are a bit off – for instance, the
some messing around on Google Großvenediger in Austria is written
Gipfel can show labels
Maps and Wikipedia, you could as “Gross Venediger”.) Now for mountains behind Peak again, dragging the icon to the
probably find the name of the right-click on the picture and the ones in the picture, other known mountain. If all is well,
mountain in question, but Gipfel choose Find Peak. Enter the name so reduce the visibility Gipfel will calculate the location
makes it easier – and more fun. of the mountain again, click OK, and setting to make things from which you took the photo, and
Using FLTK for the interface, a red symbol will appear. Drag this clearer. add labels to the tops of other
Gipfel’s dependencies are libtiff4- to the top of the known mountain. mountains in the picture.
dev, libjpeg62-dev, libexiv2-dev, Now repeat this process, It’s possible to manually adjust
libgsl0-dev and libfltk1.3-dev. right-clicking and choosing Find your latitude and longitude, and also
Once you have the program started, tweak various angles and settings

“Gipfel will add labels to the tops
click File > Load Image in the menu, to match your photo more closely.
and select a photo from your It’s a clever little app when it works
collection. Choose a picture that
includes several distinct peaks,
of other mountains in the picture.” correctly – it just takes some
fiddling to get right.

Text-mode web browser

Lynx 2.8.8
http://lynx.isc.org

W
e love programs that run attempt to recreate complex
on almost every OS layouts, but for text-heavy sites it
under the sun. Lynx, the does a respectable job.
venerable text-mode web browser
that has been doing the rounds Bare-bones browser
since 1992, has just seen a new The only major requirement to build
release. And this release has been Lynx is (n)curses. Once you have it
tested on (deep breath): Linux, running, hit G to enter a URL. Use
FreeBSD, NetBSD, OpenBSD, the cursor keys to navigate through
Hit O to bring up the
OpenVMS, AIX, HP-UX, Haiku, IRIX, links, enter to follow a link, the left commands; a progress bar that’s
options screen, which
Solaris, Tru64, Mac OS X, and even cursor key to go back, and Ctrl+P/N is full of tweakable bits now compiled in by default and
that weird Windows thing that to scroll two lines backwards/ ’n’ bobs. available in the options screen;
some people still use. forwards. Hit Shift+G to edit the improvements to SSL support; and
Now, Lynx is quite limited as a current URL, backspace to bring up better interpretation of HTML code.
web browser, given that it operates the history, and forward slash to do We’re really chuffed to see Lynx
in text mode, but it’s good to have a search. Lynx has an impressive being updated to support the latest
around. If something goes wonky range of features tucked away - so web technologies – it’s good to
with your X server and you need to enter H to bring up the help. When know that it’s always there, even
search the web for help or drivers, you’re finished, Q quits. when you’re exploring some
you’ll need a browser that runs in New features in version 2.8.8 random, obscure Unix variant that
the plain text terminal. Lynx doesn’t include: submit, reset and pwd few people have heard of.

www.linuxvoice.com 69
FOSSPICKS

PDF and PostScript file annotator

Flpsed 0.7.2
www.flpsed.org/flpsed.html

D
espite the best efforts of the Flpsed is a super-simple
Free Software community, lightweight little app that lets you
people still send Microsoft add text to PDF and PostScript
Word .doc files around as if they documents, without changing the
were some kind of standard. We structure of them. You simply add
always recommend that people lines of text at whatever position
install LibreOffice and use an open you want, and then re-export the file
file format, but our words often fall as a PDF. This means you can fill in
on deaf ears. Usually, the best forms in seconds without having Flpsed doesn’t alter the structure of PDF documents - it just adds
success we have is asking people to mess around in a much more another layer of text on top.
to send us documents as PDFs – complicated app.
at least they will render the same It’s built with FLTK, and has a document, and start typing. When
across different platforms. very sparse interface: click File > you’re done, click File > Export PDF.
Now, that’s all good and well until Open File and choose a document. This is good enough, but Flpsed
someone sends you a form to fill in. Then set your font size and colour has an awesome extra feature:
If your PDF reader doesn’t support using the widgets in the toolbar, batch processing. It’s possible to
this facility, you might be tempted click on the relevant position in the add tags to PDFs that will later be
to install the dreadfully bloated replaced by custom text strings, so
Adobe Reader, which makes
your hard drive grind on start-up “You simply add lines of text, then you can, for instance, automatically
add text to a bunch of forms
and perpetually annoys you with
“update me!” pop-ups.
re-export the file as a PDF.” without having to go through each
one manually.

Security auditing tool

Lynis 1.4.1
http://cisofy.com/lynis

S
ecurity is a moving target: you existence) and can be executed in
can harden your systems to place without installation. To use it
an almost unbreakable all you need to enter is:
degree, but there’s no guarantee tar xfv lynis-1.4.1.tar.gz
that they’ll be equally robust cd lynis-1.4.1/
tomorrow, when new vulnerabilities sudo ./lynis -c
are discovered. It’s also a vast topic, (The -c flag performs a complete
and if you’ve been given the job of check – just run sudo ./lynis on its
making a Linux box ultra secure, it’s own to see all available options.) Lynis doing a scan: it
hard to know where to start. You’ve Lynis works step-by-step through has some suggestions colours: green means that
got packages to update, user different aspects of your setup, for user and group everything’s OK, yellow is used for
accounts to maintain, settings in pausing along the way to help you settings, which it will warnings, and red signifies major
/etc to check… it adds up. see what’s going on. It looks at explain in more detail at problems. Once the scan has
the end.
Lynis provides a one-stop-shop potential problems in user and completed, you’re given a much
for checking your system’s security. group settings, looks for vulnerable more detailed set of instructions for
It’s a script that pokes around in packages, checks file permissions, fixing issues that have cropped up.
various parts of your Linux tests your networking setup, looks Lynis is no silver bullet and won’t
installation, alerting you to potential at your compiler configuration, and make your machines impenetrable,
problems. Usefully, it’s written in many other things. but it’s well worth keeping around
plain shell script (so it will run on As the scan progresses, Lynis and running periodically to keep one
virtually every Linux distro in provides feedback in different step ahead of crackers.

70 www.linuxvoice.com
FOSSPICKS

FOSSPICKS Brain relaxers
Deliberately annoying Tetris variant

NightmareTris 1.0
https://github.com/giacomodrago/nightmaretris

T
etris does funny things to of love and liblove available in
your brain. Play it for long Ubuntu 13.10’s repositories don’t
enough, and you’ll start work properly with the game, so
to wonder if the game is trying to if you’re using that distro, get the
taunt you, giving you especially latest packages from www.love2d.
awkward pieces at the most org. Then run the game as follows:
difficult moments. In reality, most love NightmareTris.love
Tetris variants pick pieces at (Add --windowed to the end of the
random, so you just have to hope command to disable full-screen
that your luck is in. NightmareTris mode.) Hit F2, and a standard-
How many times are
is different though: it includes looking game of Tetris begins: use Sometimes the game doesn’t
we going to get a 2x2
an algorithm that deliberately the left and right cursor keys to block? Until we lose the seem to be too evil, but you know
chooses the worst pieces for move pieces sideways, up to rotate game, clearly… that it’s only planning to make
your current situation. Need the them, and down to drop the piece your life harder down the line.
long thin one to get rid of four to the bottom. If you enjoy a spot of Tetris
lines? You ain’t going to get it… but got bored with the standard
As well as being annoying to Curse my metal body! variants years ago (how could
play, NightmareTris is a bit fiddly There’s no music or fancy effects, you?!), it’s well worth trying this.
to install. It’s written using LÖVE, but the gameplay is great: it’s Don’t punch your monitor too
a 2D game engine; the versions classic Tetris, made extra difficult. hard though…

Souped-up Tron-like game

Zatacka X 0.1.6
https://github.com/simenheg/zatackax

W
e’ve seen countless Ubuntu-based systems you can get
Tron-inspired games these via libsdl1.2-dev, libsdl-
come and go over the mixer1.2-dev, libsdl-ttf2.0-dev and
years, and they’re all pretty much libsdl-image1.2-dev.
the same: you control a moving Build the game with make and
dot that leaves a path behind it, run it in place with ./zatackax. The
and CPU-controlled opponents game is set up for multiplayer, but if
also zip around, leaving trails on you want to play against the
the screen. Your goal is to survive computer, go to Settings > Player
Trails occasionally have
for as long as possible without Config and set the AI for extra opponents. Hit Enter again to
gaps in them, leaving
crashing into any of the trails. players to On. At the main screen, possible escape routes start playing. Use the left and
Zatacka X takes a slightly highlight Start Game and press the when the arena starts to right keys to change the direction
different approach; it’s based on a right arrow key to add the AI players get full. of your line, and up to use a
game called “Achtung, die Kurve” you just enabled, then hit Enter. power-up. You’ll notice your line
(watch out for the curve) with changes direction in a smooth
some extra goodies sprinkled on Race against the machine curve, rather than at right-angles
top. Getting it compiled is fairly Before the game begins, there’s a like in other Tron-esque games,
simple as it just depends on choice of power ups: these give you and the power ups make it much
common SDL libraries: in Debian/ temporary boosts, or afflict your more entertaining.

www.linuxvoice.com 71
Email andrew@linuxvoice.com to advertise here
TUTORIALS INTRO

TUTORIALS
Dip your toe into a pool full of Linux knowledge with eight
tutorials lovingly crafted to expand your Linux consciousness.

In this issue…
74 76

Ben Everard Bug reporting Pi arcade
is now developing a secret receipe for the Get gaming on Linux without
ultimate porter ale. You don’t have to program to help make
open source software. Ben Everard a trace of Valve’s SteamOS in
introduces bug reporting. sight – with Graham Morrison.

Y
ou lot were pretty keen to get
issue 1. As soon as we put it
online for subscribers, our web 82 86 92
server was hit pretty hard. Not enough
to take it offline, but enough to slow it
down. Not that we noticed of course,
we were too busy trying to work out
why some people couldn’t get access,
and why some subscribers’ email
addresses weren’t working (it all seems Grace Hopper KDE konﬁg UEFI
to be OK now). Once the dust had
Juliet Kemp uncovers Build the perfect KDE Conquers the controversial
settled, we needed to work out how our
programming on the desktop for you – with boot technique – also with
server had coped.
UNIVAC in 1950s America. Graham Morrison Graham Morrison.
We turned to our sysadmin toolkit to
ﬁnd out. Piwik (our analytics platform)
kept logs of how long it took pages to
load, and Sar kept track of how much PROGRAMMING
the processor power was being used.
They’re both great open source tools Drawing fractals Key distribution Linux kernel
that make the life of a sysadmin so Picasso, Monet and Encrypted communication The Linux kernel is the
96 100 102
much easier. I’ve been using Linux for Michaelangelo all used paint is a great way to protect product of the combined
and brushes. The fools! It’s far your privacy online, but how you effort of thousands of people. If
well over a decade, but they’re both new
better to create pretty pictures by you get the keys to everyone in the you want to join the illustrious
to me, and proof that we can always writing Python code. How, you ﬁrst place? After all, without keys, ranks of kernel developers, the ﬁrst
keep learning new things in Linux. ask. Well, with nothing more than encryption is useless. Through the step is learning how it all works.
(In case you’re wondering, our page a few loops and recursions, wonders of mathematics and We’ll walk you through the basics,
load times slowed from about 0.5 beautiful canvases can bloom physics, you can foil the feds as and help you get started. Together
from underneath a turtle… they attempt to listen in. we can make it even better.
seconds to almost 0.8 seconds, and the
processor usage barely topped 30%.)

www.linuxvoice.com 73
TUTORIAL BUG REPORTS

FILING EFFECTIVE
TUTORIAL
BUG REPORTS
Found a mistake in your favourite software? Share the knowledge,
BEN EVERARD
help the developers out and we can all help make software better.

A
bug is an incorrect behaviour in a piece of website and find out how to report bugs. Larger
WHY DO THIS? software. This could be anything from the projects will usually have a website describing what to
• Feel the warm glow program crashing, to not rendering graphics do, and any information in that obviously supersedes
of helping your fellow
Linux users. properly to small things like spelling mistakes in the any general advice we give here. If there isn’t a bug
• Gain an insight into user interface. They’re a fact of life for anyone who tracker, you’ll need to email either the developer or a
how Free Software uses computers and no software is completely mailing list with information about the problem.
development works. immune to them. Open source software will get a lot There’s no point in flooding bug trackers with
• Have a say in how your better if people help the developers by filing good bug duplicate reports, so before you submit anything,
favourite software
progresses. reports, because unless developers know what the check to see if the problem is already on the system.
problems are, they can’t fix them. A bug tracker should let you search the current
The most important thing with bug reports is to not reports, while projects without trackers often have
be afraid of them. Anyone who’s written software information about known problems in release notes,
knows that bugs are a part of life and they won’t be or elsewhere on their website.
mortally offended by the suggestion that their
software is somehow imperfect. In fact, they’ll Filling a report
probably be grateful for the feedback. Regardless of the bug you’ve found, there are a few
There are a few pieces of information that you absolutely must

“Public bug reporting is an simple things that can
make bug reports
include for the report to be useful at all. This is the
version of the software you’re using, the operating
essential part of the free much more useful, and system you’re running, and information about the

software development cycle.” we’ll have a look at
these here. The first
hardware you’re running on. Most of the time, there
will be specific fields in the bug tracker that you need
step, though, is to to fill in for this. After that, there is usually a text box
make sure you have the latest version of the software. where you can enter a description of the problem.
You should upgrade through your package manager. The key to a good bug report is reproducibility. If a
If possible, you should check the latest version on the developer can’t reproduce the bug, they can’t
program’s web page, and install this if it’s more recent. investigate it and they certainly can’t test if a fix works.
Bugzilla (a bug tracker
As far as filing bug reports are concerned, there are If you come across a bug, the first step is to make
developed by Mozilla) is
one of the most common two types of software: those with bug trackers and sure you know what caused it. This means shutting
bug management tools those without. Bug trackers are databases of bug down the software, then re-tracing your steps to see if
used in open source information, typically with a web front-end. If you it happens again. If it does, these are the steps you
projects. notice a bug, the first stage is to go to the project’s need to enter into the bug report. If it doesn’t, you need
to look a little bit harder to see what triggered the bug.
Take a look at these two reports:
“Yo, LibreOffice devs. The software breaks when I try to use
a picture. Betta fix it quick or I’m movin back to MS Office”
and
“LibreOffice Writer is crashing when inserting a picture into
a document. Steps to reproduce:
Open LibreOffice Writer
Go to File > New > Text Document
Go to Insert > Image > From File and select image. Note
this isn’t happening with all images. I’ve attached an image
that is causing a problem
At this point, the window becomes unresponsive
This worked fine In LibreOffice 4.1, but has stopped
working in LibreOffice 4.2”
(This is only an example, LibreOffice doesn’t have a
problem with image import.)

74 www.linuxvoice.com
TUTORIAL BUG REPORTS

The top report is missing loads of key information.
What does ‘use an image’ mean? What piece of the
LibreOffice suite are they using? What image are they
using? Without knowing this, there’s simply no way to
investigate the problem.
You might look at the bottom one and think that the
steps are a bit simplistic. After all, surely a LibreOffice
developer knows how to insert an image without
step-by-step instructions? They probably do, but with
most software, there’s more than one way to
accomplish a task, so it helps to go through
everything in little steps. Nothing is too basic to be
included in a bug report! Also remember that English
may not be the developer’s first language, so try to
keep it as clear as possible.
Most bug trackers also enable you to attach files,
and these are a great way of providing the developers
with the information they need. In the above example,
GitHub (shown here)
we attached an image that caused the problem. As a If you’re unsure about anything in a bug report,
and most other popular
general rule, you should include any files that are most projects have an IRC (Internet Relay Chat) source code management
involved in reproducing the bug (make sure they don’t channel, and this is usually the best place to get platforms also have bug
include any confidential information). Screenshots of answers to problems like this, though this does vary trackers for the software
the problem happening are often useful as well, from project to project. they host.
though not always possible if the program is crashing.
Fixing the problem
After the report is filed It’s possible that the developer will reject the bug. This
What happens after the bug is filed will depend on the could be because the problem is caused by
project. On smaller projects, it may go straight to a something other than the software itself (such as
developer who will look into it. In larger projects, they incorrect configuration), or because they don’t think
will often be triaged by a bugfixing team who will try to it’s a problem (for example, you could be doing
reproduce the bug before assigning it to the right something outside of the program’s intended use).
development team. Hopefully, though, the bug will be accepted and
It’s important for you, as the bug submitter, to keep looked into by the development team. Usually, they’ll
an eye on the bug report at this stage because they release a fix and ask you (the bug submitter) to test it
may need more information in order to reproduce the to see if it works. This obviously won’t go straight into
bug. Depending on the problem, they may also your distro’s package manager, so you’ll usually need
suggest a workaround so that you can side-step the to compile the new source code with this fix in. After
bug until it’s fixed. this, you should update the bug with information
about whether the fix has worked or not.
If all goes to plan, the final step is to mark the bug
Get more involved as resolved in the bug tracker (see the project’s
documentation for details of how to do this), or letting
If you want to get more involved in testing open source
software, most large open source projects are looking for the developer know that it’s worked.
volunteers to help out. This can include working on bug There is one exception to the bug submission
hunts before big launches or helping triage and investigate process we’ve talked about here: security issues. Most
reported bugs. It’s a great way to contribute to a project, bug trackers are public, so you shouldn’t post any
and it doesn’t require any programming skill.
information that could be used to exploit the system,
LibreOffice is an excellent place to start. The team are
incredibly friendly to new testers, and they have a three-day unless the project’s documentation explicitly tells you
bug hunting session before each point release. The last one to. If you find a security issue, look at the software’s
(before 4.2) was in December, and you can see details website for guidance, or email the developers directly.
about it on the project website (https://wiki. It is possible to track security issues with CVEs
documentfoundation.org/BugHunting_Session_4.2.0).
(Common Vulnerabilities and Exposures) numbers,
Keep an eye on The Document Foundation’s blog
(http://blog.documentfoundation.org) for details of but this isn’t essential.
upcoming events. Alternatively, you could start using beta Filing a bug report doesn’t take long, and you should
releases of software that’s important to you. These early recoup that time by having working software once the
releases tend to have more bugs in them than final releases, bug’s fixed. Public bug reporting is an essential part of
and they need people like you to find all these problems so
the free software development cycle. It doesn’t matter
they can be fixed before the final release. What’s more, it
gives you (as a user) a chance to make sure that new if you’ve never touched a line of code in your life – by
versions will work properly on your setup with your data. helping the developers, you can contribute to the free
software community and we’ll all benefit.

www.linuxvoice.com 75
TUTORIAL RASPBERRY PI ARCADE MACHINE

BUILD A RASPBERRY PI
TUTORIAL
ARCADE MACHINE
Relive the golden majesty of the 80s with a little help from a
GRAHAM MORRISON
marvel of the current decade.

T
he 1980s were memorable for many things;
WHAT YOU’LL NEED the end of the cold war, a carbonated drink
• Raspberry Pi w/4GB called Quatro, the Korg Polysix synthesiser
SD-CARD.
and the Commodore 64. But to a certain teenager,
• HDMI LCD monitor.
none of these were as potent, or as perhaps familiarly
• Games controller or…
illicit, as the games arcade. Enveloped by cigarette
• A JAMMA arcade
cabinet. smoke and a barrage of 8-bit sound effects, they were
• J-Pac or I-Pac. caverns you visited only on borrowed time: 50 pence
and a portion of chips to see you through lunchtime
while you honed your skills at Galaga, Rampage,
Centipede, Asteroids, Ms Pacman, Phoenix, R-Rype,
DISCLAIMER Donkey Kong, Rolling Thunder, Gauntlet, Street Fighter,
Outrun, Defender… The list is endless.
One again we’re
messing with electrical These games, and the arcade machine form factor
components that could that held them, are just as compelling today as they
cause you a shock. were 30 years ago. And unlike the teenage version
Make sure you get any of yourself, you can now play many of them without
modifications you make
checked by a qualified needing a pocket full of change, finally giving you an
electrician. We don’t go edge over the rich kids and their endless ‘Continues’.
into any details on how It’s time to build your own Linux-based arcade
to obtain games, but
machine and beat that old high score.
there are legal sources
such as old games We’re going to cover all the steps required to turn
releases and newer a cheap shell of an arcade machine into a Linux-
commercial titles based powered multi-platform retro games system. But that
on the MAME emulator.
doesn’t mean you’ve got to build the whole system
at the same scale. You could, for example, forgo the
large, heavy and potentially carcinogenic hulk of the
cabinet itself and stuff the controlling innards into an
old games console or an even smaller case. Or you
could just as easily forgo the diminutive Raspberry Pi
and replace the brains of your system with a much
more capable Linux machine. This might make an
ideal platform for SteamOS, for example, and for
playing some of its excellent modern arcade games.
Over the next few pages we’ll construct a Raspberry
Pi-based arcade machine, but you should be able to
see plenty of ideas for your own projects, even if they
don’t look just like ours. And because we’re building it Cabinets can be cheap, but they’re heavy. Don’t lift them
on the staggeringly powerful MAME, you’ll be able to on your own. Older ones may need some TLC, such as a
get it running on almost anything. re-spray and some repair work.

1 THE CABINET
The cabinet itself is the biggest challenge. We bought other end of the scale, people pay thousands for
an old two-player Bubble Bobble machine from the machines with original decals on the side.
early 90s from eBay. It cost £220 delivered in the back There are two major considerations when it comes
of an old estate car. The prices for cabinets like these to buying a cabinet. The first is the size: These things
can vary. We’ve seen many for less than £100. At the are big and heavy. They take up a lot of space and it

76 www.linuxvoice.com
RASPBERRY PI ARCADE MACHINE TUTORIAL

takes at least two people to move them around. If We took the coward’s
you’ve got the money, you can buy DIY cabinets or route, and replaced the
new smaller form-factors, such as cabinets that fit on CRT with a piece of MDF
tables. And cocktail cabinets can be easier to fit, too. and a VESA mount for a
more modern (lighter, less
One of the best reasons for buying an original
lethal) screen.
cabinet, apart from getting a much more authentic
gaming experience, is being able to use the original
controls. Many machines you can buy on eBay will be
for two concurrent players, with two joysticks and a
variety of buttons for each player, plus the player one
and player two controls. For compatibility with the
widest number of games, we’d recommend finding a
machine with six buttons for each player, which is a
common configuration. You might also want to look
into a panel with more than two players, or one with
space for other input controllers, such as an arcade
trackball (for games like Marble Madness), or a transfer your twitches and tweaks into game
spinner (Arkanoid). These can be added without too movement. What you need to consider for when
much difficulty later, as modern USB devices exist. buying a cabinet is something called JAMMA, an
Controls are the second, and we’d say most acronym for Japan Amusement Machinery
important consideration, because it’s these that Manufacturers. JAMMA is a standard in arcade
machines that defines how the circuit board PRO TIP
containing the game chips connects to the game
For a cheap input
controllers and the coin mechanism. It’s an interface interface, buy a PS3 USB
conduit for all the cables coming from the buttons controller, dismantle it
and rewire the switches
and the joysticks, for two players, bringing them into a
to connect to those on
standard edge connector. The JAMMA part is the size your cabinet.
and layout of this connector, as it means the buttons
and controls will be connected to the same functions
on whichever board you install so that the arcade
owner would only have to change the cabinet artwork
to bring in new players.
But first, a word of warning: the JAMMA connector
also carries the 12V power supply, usually from a
power unit installed in most arcade machines. We
Another concession disconnecting the power supply completely to avoid
to safety was the
damaging anything with a wayward short-circuit or
disconnection of the
dropped screwdriver. We don’t use any of the power
old power supply.
connectors in any further stage of the tutorial.

RASPBERRY PI ARCADE SURVIVAL KIT

Raspberry Pi: Powered
Any Pi will do, hub: A USB 2
but a Model B powered hub
with USB and is essential for
Ethernet is the anything you
best option. do with the
Raspberry Pi.

4GB SD card:
4GB is the HDMI cable:
minimum, and Arcade monitors
you could choose Controllers: You don’t need
can be made to
to store games an arcade machine. A cheap
work, but it’s a
on the network USB converter and an old
crazy hack. The
or a USB storage generation console controller
easy option is to
device is almost as good.
use HDMI or DVI.

www.linuxvoice.com 77
TUTORIAL RASPBERRY PI ARCADE MACHINE

2 J-PAC
What’s brilliant is that you can buy a device that
connects to the JAMMA connector inside your
cabinet and a USB port on your computer,
transforming all the buttons presses and keyboard
movements into (configurable) keyboard commands
that you can use from Linux to control any game you
wish. This device is called the J-Pac (www.ultimarc.
com/jpac.html – approximately £54).
Its best feature isn’t the connectivity; it’s the way it
handles and converts the input signals, because it’s
vastly superior to a standard USB joystick. Every input
generates its own interrupt, and there’s no limit to the
number of simultaneous buttons and directions you
can press or hold down. This is vital for games like
Street Fighter, because they rely on chords of buttons
PRO TIP
being pressed simultaneously and quickly, but it’s also Our J-Pac in situ. The blue and red wires on the right
If you replace the Pi with
a PC, you can configure
essential when delivering the killing blow to cheating connect to the extra 1- and 2-player buttons on our cabinet.
it from the BIOS to players who sulk and hold down all their own buttons.
automatically boot when Many other controllers, especially those that create control to the I-Pac yourself. This might be a little
it gets some power.
keyboard inputs, are restricted by their USB keyboard ambitious for a first project, but it’s a route that many
controllers to six inputs and a variety of Alt, Shift and arcade aficionados take, especially when they want to
Ctrl hacks. The J-Pac can also be connected to a tilt design a panel for four players, or one that
sensor and even some coin mechanisms, and it incorporates many different kinds of controls. Our
works in Linux without any pre-configuration. approach isn’t necessarily one we’d recommend, but
Another option is a similar device called an I-Pac. It we re-wired an old X-Arcade Tankstick control panel
does the same thing as the J-Pac, only without the that suffered from input contention, replaced the
JAMMA connector. That means you can’t connect joysticks and buttons with new units and connected it
your JAMMA controls, but it does mean you can to a new JAMMA harness, which is an excellent way
design your own controller layout and wire each of buying all the cables you need plus the edge
connector for a low price (£8).
JAMMA connections
Get connected
PIN TOP BOTTOM Whether you choose an I-Pac or a J-Pac, all the keys
1 GND GND generated by both devices are the default values for
2 GND GND MAME. That means you won’t have to make any
3 +5V +5V
manual input changes when you start to run the
4 +5V +5V
5 -5V -5V emulator. Player 1, for example, creates cursor up,
6 +12V +12V down, left and right as well as left Ctrl, left ALT, Space
7 lock/key lock/key and left Shift for fire buttons 1–4. But the really useful
8 counter 1 counter 2 feature, for us, is the two-button shortcuts. While
9 lockout lockout
holding down the player 1 button, you can generate
10 speaker + speaker -
11 not used not used the P key to pause the game by pulling down on the
12 CRT red CRT green player 1 joystick, adjust the volume by pressing up
13 CRT blue CRT sync and enter MAME’s own configuration menu by
14 video GND service pushing right. These escape codes are cleverly
15 test tilt
engineered to not get in the way of playing games, as
16 coin 1 coin 2
17 P1 start P2 start they’re only activated when holding down the Player 1
18 P1 up P2 up button, and they enable you to do almost anything you
19 P1 down P2 down need to from within a running game. You can
20 P1 left P2 left completely reconfigure MAME, for example, using its
21 P1 right P2 right
own menus, and change input assignments and
22 P1 B1 P2 B1
23 P1 B2 P2 B2 sensitivity while playing the game itself.
24 P1 B3 P2 B3 Finally, holding down Player 1 and then pressing
25 P1 B4 P2 B4 Player 2 will quit MAME, which is useful if you’re using
26 not used not used a launch menu or MAME manager, as these manage
27 GND GND
launching games automatically, and let you get on
28 GND GND
with playing another game as quickly as possible.

78 www.linuxvoice.com
RASPBERRY PI ARCADE MACHINE TUTORIAL

We took a rather cowardly route with the screen, You might also want to look into using an older LCD
removing the original, bulky and broken CRT that with a 4:3 aspect ratio, rather than the widescreen
came with the cabinet and replacing it with a low-cost modern options, because 4:3 is more practical for
LCD monitor. This approach has many advantages. playing both vertical and horizontal games. A vertical
First, the screen has HDMI, so it will interface with a shooter such as Raiden, for example, will have black
Raspberry Pi or a modern graphics card without any bars on either side of the gaming area if you use a
difficulty. Second, you don’t have to configure the widescreen monitor. Those black bars can be used to
low-frequency update modes required to drive an display the game instructions, or you could rotate the
arcade machine’s screen, nor do you need the specific screen 90 degrees so that every pixel is used, but this
graphics hardware that drives it. is impractical unless you’re only going to play vertical
games or have easy access to a rotating mount.
Minimise risk of death Mounting a screen is also important. If you’ve
And third, this is the safest option because an arcade removed a CRT, there’s nowhere for an LCD to go. Our
machine’s screen is often unprotected from the rear solution was to buy some MDF cut to fit the space
of a case, leaving very high voltages inches away from where the CRT was. This was then screwed into
your hands. That’s not to say you shouldn’t use a CRT position and we fitted a cheap VESA mounting plate
if that’s the experience you’re after – it’s the most into the centre of the new MDF. VESA mounts can be
authentic way to get the gaming experience you’re used by the vast majority of screens, big and small.
after, but we’ve fined-tuned the CRT emulation enough Finally, because our cabinet was fronted with smoked
in software that we’re happy with the output, and glass, we had to be sure both the brightness and
we’re definitely happier not to be using an ageing CRT. contrast were set high enough.

3 INSTALLATION
With the large hardware choices now made, and
presumably the cabinet close to where you finally Our Raspberry Pi is now
want to install it, putting the physical pieces together connected to the J-Pac
isn’t that difficult. We safely split the power input from on the left and both the
the rear of the cabinet and wired a multiple socket into screen and the USB hub.
the space at the back. We did this to the cable after it
connects to the power switch.
Nearly all arcade cabinets have a power switch
on the top-right surface, but there’s usually plenty of
cable to splice into this at a lower point in the cabinet,
and it meant we could use normal power connectors
for our equipment. Our cabinet has a fluorescent tube,
used to backlight the top marquee on the machine,
connected directly to the power, and we were able to
keep this connected by attaching a regular plug. When
you turn the power on from the cabinet switch, power
flows to the components inside the case – your
Raspberry Pi and screen will come on, and all will be
well with the world.

The creation takes shape
The J-Pac slides straight into the JAMMA interface, amplifier and connected this to the audio outputs on
but you may also have to do a little manual wiring. The the Raspberry Pi. You don’t want audio to be pristine,
JAMMA standard only supports up to three buttons but you do want it to be loud enough.
for each player (although many unofficially support The J-Pac or I-Pac then connects to your PC or
four), while the J-Pac can handle up to six buttons. Raspberry Pi using a PS2-to-USB cable, which should
To get those extra buttons connected, you need to also be used to connect to a PS2 port on your PC
connect one side of the button’s switch to GND fed directly. There is an additional option to use an old
from the J-Pac with the other side of the switch going PS2 connector, if your PC is old enough to have one,
into one of the screw-mounted inputs in the side of but we found in testing that the USB performance is
the J-Pac. These are labelled 1SW4, 1SW5, 1SW6, identical. This won’t apply to the PS2-less Raspberry
2SW4, 2SW5 and 2SW6. The J-Pac also includes Pi, of course, and don’t forget that the Pi will also
passthrough connections for audio, but we’ve need powering. We always recommend doing so
found this to be incredibly noisy. Instead, we wired from a compatible powered hub, as a lack of power
the speaker in our cabinet to an old SoundBlaster is the most common source of Raspberry Pi errors.

www.linuxvoice.com 79
TUTORIAL RASPBERRY PI ARCADE MACHINE

You’ll also need to get networking to your Raspberry it enables you to reconfigure your PI while it’s tucked
Pi, either through the Ethernet port (perhaps using a away within the cabinet, and it also enables you to
powerline adaptor hidden in the cabinet), or by using a change settings and perform administration tasks
wireless USB device. Networking is essential because without having to connect a keyboard or mouse.

Coin mechanism
In the emulation community, getting your its value. It does this with the help of a credit/ Whichever system you choose, we’ve found
coin mechanism to work with your emulator logic board, usually attached via a ribbon a working coin mechanism to be the perfect
was often considered a step too close to cable and featuring lots of DIP switches. piggy bank as long as you don’t raid the coin
commercial production. It meant you could These switches are used to change which reservoir too often, or lose the keys.
potential charge people to use your machine. coins are accepted and how many credits
Not only would this be wrong, but considering they generate. It’s then usually as simple as
the provenance of many of the games you finding the output switch, which is triggered
run on your own arcade machine, it could with a credit, and connecting this to the coin
also be illegal. And it’s definitely against the input on your JAMMA connector, or directly
spirit of emulation. However, we and many onto the J-Pac. Our coin mechanism is a Mars
other devotees thinking that a working coin MS111, common in the UK in the early 90s,
mechanism is another step closer to the and there’s plenty of information online about
realism of an arcade machine, and is worth what each of the DIP switches do, as well as
the effort in recreating the nostalgia of an old how to programme the controller for newer
arcade. There’s nothing like dropping a 10p coins. We were also able to wire the 12V
piece into the coin tray and to hear the sound connector from the mechanism to a small
of the credits being added to the machine. light for behind the coin entry slot.
It’s not actually that difficult. It depends We’ve not been able to try one, but
on the coin mechanism in your arcade apparently the 25-cent coin mechanism used
machine and how it sends a signal to say how by nearly all arcade machines in the USA
many credits had been inserted. Most coin throughout the 80s, and built by HAPP, are
mechanisms come in two parts. The large even easier to use. These embed a simple Our programmable coin mechanism is a Mars
part is the coin acceptor/validator. This is microswitch into the coin path, and wiring MS111. It accepts 10p, 20p, 50p and £1 coins
the physical side of the process that detects this to your JAMMA connector will create a and will send credit pulses at regular intervals
whether a coin is authentic, and determines credit whenever an accepted coin is inserted. to the JAMMA connector.

4 SOFTWARE
MAME is the only viable emulator for a project of enables you to install new games through a browser
this scale, and it now supports many thousands connected to your network. This is a great advantage,
of different games running on countless different because getting games into the correct folders is
platforms, from the first arcade machines through to one of the trials of dealing with MAME, and it also
some more recent ones. It’s a project that has also enables you to make best use of whatever storage
spawned MESS, the multi-emulator super system, you’ve got connected to your Pi. Plus, PiMAME will
which targets platforms such as home computers update itself from the same script you use to install
PRO TIP
and consoles from the 80s and 90s. it, so keeping on top of updates couldn’t be easier.
MAME is not actually
Free Software. It uses Configuring MAME could take a six-page article This could be especially useful at the moment, as
a modified version in itself. It’s a complex, sprawling, magnificent at the time of writing the project was on the cusp of
of the BSD licence to piece of software that emulates so many CPUs, a major upgrade in the form of the 0.8 release. We
restrict commercial
redistribution. so many sound devices, chips, controllers with so found it slightly unstable in early March, but we’re sure
many options, that like MythTV, you never really stop everything will be sorted by the time you read this.
configuring it.
But there’s an easier option, and one that’s purpose- Install MAME the easy way
built for the Raspberry Pi. It’s called PiMAME. This The best way to install PiMAME is to install Raspbian
is both a distribution download and a script you can first. You can do this either through NOOBS, using
run on top of Raspbian, the Pi’s default distribution. a graphical tool from your desktop, or by using the
Not only does it install MAME on your Raspberry Pi dd command to copy the contents of the Raspbian
(which is useful because it’s not part of any of the image directly onto your SD card. As we mentioned
default repositories), it also installs a selection of other in last month’s BrewPi tutorial, this process has
emulators along with front-ends to manage them. been documented many times before, so we won’t
MAME, for example, is a command-line utility with waste the space here. Just install NOOBS if you
dozens of options. But PiMAME has another clever want the easy option, following the instructions on
trick up its sleeve – it installs a simple web server that the Raspberry Pi site. With Raspbian installed and

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RASPBERRY PI ARCADE MACHINE TUTORIAL

running, make sure you use the configuration tool to
free the space on your SD card, and that the system
is up to date (sudo apt-get update; sudo apt-get
upgrade). You then need to make sure you’ve got the
git package already installed. Any recent version of
Raspbian will have installed git already, but you can
check by typing sudo apt-get install git just to check.
You then have to type the following command to
clone the PiMAME installer from the project’s GitHub
repository:
# git clone https://github.com/ssilverm/pimame_installer
After that, you should get the following feedback if the
command works:
Cloning into ‘pimame_installer’...
remote: Reusing existing pack: 2306, done.
remote: Total 2306 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (2306/2306), 4.61 MiB | 11 KiB/s, done.
Resolving deltas: 100% (823/823), done.
The latest version of
This command will create a new folder called for the existence of /dev/input/by-id/usb-Ultimarc_I-
PiMAME (0.8) has a
‘pimame_installer’, and the next step is to switch into PAC_Ultimarc_I-PAC-event-kbd. great user interface that
this and run the script it contains: The default keyboard controls will enable you to works well with an arcade
cd pimame_installer/ select what kind of emulator you want to run on your machine.
sudo ./install.sh arcade machine. The option we’re most interested in
This command installs and configures a lot of is the first, labelled ‘AdvMAME’, but you might also be
software. The length of time it takes will depend on surprised to see another MAME on offer, MAME4ALL.
your internet connection, as a lot of extra packages MAME4ALL is built specifically for the Raspberry Pi,
are downloaded. Our humble Pi with a 15Mb internet and takes an old version of the MAME source code
connection took around 45 minutes to complete so that the performance of the ROMS that it does
the script, after which you’re invited to restart the support is optimal. This
machine. You can do this safely by typing sudo
shutdown -r now, as this command will automatically
makes a lot of sense,
because there’s no way
“After rebooting, you will be
handle any remaining write operations to the SD card. your Pi is going to be logged in and the PiMAME
And that’s all there is to the installation. After
rebooting your Pi, you will be automatically logged
able to play anything too
demanding, so there’s no
launcher will appear.”
in and the PiMAME launch menu will appear. It’s a reason to belabour the
great-looking interface in version 0.8, with photos of emulator with unneeded compatibility. All that’s left to
each of the platforms supported, plus small red icons do now is get some games onto your system (see the
to indicate how many games you’ve got installed. boxout below), and have fun!
This should now be navigable through your controller.
If you want to make sure the controller is correctly Graham Morrison wastes too many hours of his life playing
Asteroids and weeping for his lost teenage years.
detected, use SSH to connect to your Pi and check

Step-by-step/How To Copying games to your arcade machine

1 Browse to the Pi 2 Choose the system 3 Upload the file
Open the IP address of your arcade machine in After clicking on ROM Uploader, choose the Dragging the file onto the page didn’t work for
a web browser. You can find the IP address from the destination emulator for your game. This will then us, but if you click inside the page a file requester lets
Pi by selecting the Tools menu. open a new upload page. you choose the file.

www.linuxvoice.com 81
TUTORIAL GRACE HOPPER AND UNIVAC

GRACE HOPPER AND UNIVAC:
TUTORIAL
BEFORE THERE WAS COBOL
In the days before cheap silicon chips, valves ruled the roost – and
JULIET KEMP
it took a special kind of brain to handle these magnificent beasts.

A
fter Babbage and the (never actually built) UNIVAC was programmable. The first customers
Analytical Engine in the 19th century, included the US Census Bureau and the US Air Force
computer development languished for a (who had the first on-site installation, in 1952). In
while. During the first half of the 20th century, various 1952, as a promotional stunt, they worked with CBS to
analog computers were developed, but these solved have UNIVAC predict the result of the 1952 US
specific problems rather than being programmable. In presidential election. It correctly (and quickly!)
1936, Alan Turing developed the idea of the ‘Universal predicted an Eisenhower win, beating out the pollsters
Machine’, and the outbreak of World War II shortly who had gone for Stevenson. So let’s take a look at
afterwards was a driver for work on developing these what it was and what it was doing.
machines, including UNIVAC, famously worked on by
Grace Hopper. UNIVAC: mercury and diodes
Grace Hopper, born in New York in 1906, was an UNIVAC weighed about 13 tons, and needed a whole
associate professor of mathematics at Vassar when garage-sized room to itself, with a complicated water
WWII broke out. Volunteering for the US Navy Reserve, cooling system and fans. It had 10 UNISERVO tape
she was assigned to the Bureau of Ships Computation drives for input and output, 5,200 electron (vacuum)
Project, where she worked on the Harvard Mark I tubes, 18,000 diodes, and a 1,000 word memory
project (a calculating machine used in the war effort), (more on that in a moment); it required about 125kW
from 1944–9, co-authoring several papers. of power to run. (A modern laptop uses around
In 1949, she moved to the Eckert-Mauchly 0.03kW. It also required a lot of maintenance;
Computer Corporation (later acquired by Remington replacing diodes, contacts and tubes, not to mention
Grace Hopper, who Rand, and later still by Unisys), and joined the UNIVAC keeping the cooling systems running.
studied mathematics and team. UNIVAC, which first ran in 1951, was the second UNIVAC’s memory and operational registers were
physics at Harvard and commercially available computer in the US, and the both based on mercury delay lines. The main memory
Vasser universities, at a
first designed for business and admin rather than for consisted of seven ‘long tanks’, each containing
later UNIVAC in 1960. By
scientific use. That meant that it was intended to eighteen ten-word channels. Each channel was a
Unknown (Smithsonian
Institution) (Flickr: Grace execute many simple calculations rapidly, rather than column of mercury with quartz crystals at each end,
Hopper and UNIVAC) performing fewer complex calculations. Punch-card and held 910 bits (840 bits for the words and 70 for
calculating machines already existed, but crucially, the spaces between each word). The main clock (at
2.25MHz) was in sync with the carrier wave of the
column (11.25MHz) and acted as the timer for all
UNIVAC operations.
To store data in a channel, the sending crystal (at
one end of the channel) was vibrated with the data
bits (ones and zeros) of the word. The rate was
controlled by the main clock, then the signal was
mixed with the carrier wave. The whole signal would
move through the column to the receiving crystal,
where a bunch of circuitry picked it up, amplified it,
analysed it, and sent it back to the sending crystal for
another trip through the mercury. So the data was
constantly rotating through the mercury, which meant
that you could only access a word when it popped out
at the receiving crystal end. The average access time
for a word was 222 microseconds, so a fair amount of
UNIVAC’s time involved waiting for word access, with
obvious practical programming implications.
You may have noticed that seven lots of 18
channels gives 126 channels of 10 words each; so
why only 1,000 words of memory? The remaining 26

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GRACE HOPPER AND UNIVAC TUTORIAL

channels were used for input and output buffering, for
the register, and for the vitally important mercury
temperature control. The mercury had to be at an
exact operating temperature for the correct transit
time and to avoid bit creep; from a cold start, it could
be up to half an hour before the tanks were able to
hold memory.
Control and computation operations were also run
via mercury delay lines, each tank working with a
single 12-character word. This made access much
quicker, and they also had distribution delay lines to
allow multi-bit access to characters. There were four
types of register:
Four Input/Output Synchronizers, used for the 60
word read/write buffers.
UNIVAC I at the Franklin
Three Control registers, used for controlling would be read into the input buffer, then transferred
Imstitute, Philadelphia.
program instruction flow. into memory. The operator would then set the
One two-word register (rV) used as a holding area machine back into ‘normal’ mode, hit the Start Bar,
during a two-word move. and UNIVAC would begin executing the instructions
Several of these registers were duplicated, then from memory, beginning with the first block. So the
compared bit-by-bit, to increase accuracy. programmer would have to make sure that from then
Finally, it had an operator’s console and an on in, everything that the program needed to do
oscilloscope connected. The console had switches (including reading in more instructions or data from
that allowed any of the memory locations to be tape) was referenced in the program itself. The
displayed and monitored on the oscilloscope. A operator’s role would be limited (at least in theory!) to
typewriter and printer were also connected for output. replacing tape reels as indicated by console
messages, and rescuing any minor problems such as
Programming UNIVAC a dropped tape loop. Breakpoints could be set in the
UNIVAC had quite a big instruction set, which covered code (instruction ,) to aid recovery from problems.
transferring the contents of memory into registers, Here’s a longer example from the 1954 UNIVAC
moving the contents of registers around, performing operating manual. The far-left number is the memory
operations, jumping to specific memory addresses, register that contains the instruction. Instructions
shifting contents of registers a given number of digits, were saved in memory in pairs, as shown, with the
and controlling input/output. The full list (with left-hand six-digit instruction run first, then the
explanations) is available at https://wiki.cc.gatech. right-hand six-digit instruction. In this example,
edu/folklore/index.php/UNIVAC_I_Instruction_Set. registers 100–999 contain a set of numbers, and the
Unfortunately there’s no Linux-compatible emulator code adds them all together.
(see boxout), but here is a small example, with 000 C00 099 C00 099
comments: 001 B00 099 A00 100
L00 101 002 C00 099 B00 001
loads contents of memory register 101 into register A. 003 L00 007 Q00 006
A00 102 004 A00 008 C00 001
loads contents of register 102 into register X, adds X to A. 005 000 000 U00 001
C00 103 006 900 000 U00 001
stores contents of register A into register 103, clears A. 007 B00 099 A00 999
P00 103 008 000 000 000 001
print contents of register 103 on the console printer. Line by line, here’s how that code works:
If you read last month’s article on Ada Lovelace and 000 C 099 stores register A into memory and zeroes
the Analytical Engine, this may look familiar. The it; so repeating this twice zeros register 099.
instructions (L, A, P) are made up to 3 digits with zero 001 B 099 loads register 099 into register A; A 100
padding. So if register 101 contains the value 2, and loads register 100 into register Z, then adds it to
register 102 contains the value 3, this will add 2 to 3, register A.
store 5 in register 103, and output 5 to the console. 002 C 099 stores register A (now containing A+Z) into
To run this program, it would have been typed onto register 099, and zeroes register A. B 001 loads the
a program tape as a series of numeric words contents of register 001 into register A. The contents
(‘translated’ from the programmer’s mnemonics given of register 001 are the program instructions in step
here). The tape (and any needed data tapes) would be 001; so we are preparing to alter the instructions
latched onto the UNISERVOs, and the operator would themselves.
manually set various options and begin the booting 003 L 007 loads the contents of register 007 (see step
process from the console. The first 60 instructions 007 below) into both register L and register X. Q 006

www.linuxvoice.com 83
TUTORIAL GRACE HOPPER AND UNIVAC

Grace Hopper remains Grace Hopper created the first operational compiler,
a source of quotable in 1952, while working on the UNIVAC project. Initially,
quotes, our favourite no one believed her. “I had a running compiler and
being: “It’s easier to ask nobody would touch it,” she said later. “They told me
forgiveness than it it to get computers could only do arithmetic.” In fact, the A-0
permission.”
system was more like what we would today call a
loader or a linker than a modern ‘compiler’. For A-0,
Hopper transferred all her subroutines to tape, each
identified with a call number, so that UNIVAC could
find it. She then wrote down the call numbers, and any
arguments, and this was converted into machine
code to be run directly. Effectively, A-0 allowed the
programmer to reuse code and to write in a more
human-readable way, and get the machine to do more
of the work.

Programming with A-0
The next versions were A-1 and A-2, with A-2 the first
compiler to be in more general use. I found a short
paper from a 1954 MIT course, which Hopper also
tutored. In it she describes A-2 as handling two types
of subroutine: static ones (stored in memory or on
tape, either from a general library or specific to the
problem) and dynamic ones. Dynamic subroutines
checks whether register L is equivalent to register A; if could be generated from a ‘skeleton’ stored subroutine
so, it jumps to register 006 (that is, step 006). and some specific parameters, or could be generated
004 A 008 loads the contents of register 008 into to handle data. A-2 had four phases of operation:
register X, and adds it to register A. As register A Expands/translates the provided code, adding in
currently holds the instruction from register 001, and data such as call-numbers and operation numbers. (In
register 008 holds (effectively) a single 1, this alters later compilers this translated from ‘code’ into
the instruction from register 001 to read B00 099 A00 ‘machine code’.)
101 instead of B00 099 A00 101. In other words, next Divides the result from phase 1 into segments
time we run step 001 we’ll add the contents of the which can be processed in a single storage load, and
next register in the list to our running total. C 001 creates references to each subroutine.
dumps the contents of register A back into register Creates the jump instructions needed to complete
001, so we’ve edited the program on the fly. the necessary jumps (for example between storage
005 The LHI is blank; the RHI (U 001) is an loads and subroutines) required by the result of phase.
unconditional jump back to register 001, ready to add After this phase, you have a complete description of
the next number in the list. the program, but not a complete program that can be
006: This simply stops the computer. (Remember run sequentially.
from 003: we jump here if the program is finished.) Main compilation. All subroutines are read in and
007 B 099 A 999. This instruction is never actually run. transformed as necessary from ‘general’ to ‘specific’
It is used in 003 to check against register A. If register (so any parameters are included), all jumps, reads, and
A looks like this at step 003, then we have added the writes are included, and a complete program is
final number (in register 999) and our program is done. generated which can now be run as-is.
003 will then jump to 006 and the program ends. (If you check out the PDF course notes in the
008 End of program. resources, there are some very cute line drawings
Fundamentally, this is a for loop that sums each illustrating the four phases.)
element in an array. But UNIVAC programmers had to
physically rewrite the instruction inside the loop each FLOW-MATIC & English-language programming
time. A couple of iterations later, Hopper and her team
One apparently excellent emulator for UNIVAC does produced FLOW-MATIC, which was the first English-
exist. It’s by Peter Zilahy Ingerman and is described at language-like data processing language. (Meanwhile,
www.ingerman.org/niche.htm#UNIVAC. FORTRAN was completed at IBM in 1957, and is
Unfortunately it’s written in Visual Basic 6 and only generally agreed to be the first complete compiler.)
runs on Windows. The download link on that page Here’s a quick sample of FLOW-MATIC code, taken
doesn’t work, but it can be obtained by contacting the from the FLOW-MATIC product brochure).
author on the given email address. The code above (0) INPUT INVENTORY FILE-A PRICE FILE-B ; OUTPUT
should run on it, but as it’s Windows we haven’t been PRICED-INV FILE-C UNPRICED-INV
able to test it. FILE-D ; HSP D .

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GRACE HOPPER AND UNIVAC TUTORIAL

(1) COMPARE PRODUCT-NO (A) WITH PRODUCT-NO (B) ; IF
GREATER GO TO OPERATION 10 ; More resources
IF EQUAL GO TO OPERATION 5 ; OTHERWISE GO TO
OPERATION 2 . My great thanks to Allan Reiter, whose page at
(2) TRANSFER A TO D . http://univac1.0catch.com is invaluable for technical
details of UNIVAC operation. Check it out for
(3) WRITE-ITEM D .
much more detailed info and plenty of photos and
(4) JUMP TO OPERATION 8 .
diagrams.
(5) TRANSFER A TO C .
There are some other wonderful UNIVAC resources
(6) MOVE UNIT-PRICE (B) TO UNIT-PRICE (C) .
available online:
(7) WRITE-ITEM C .
(8) READ-ITEM A ; IF END OF DATA GO TO OPERATION 14 . The 1951 ‘Introduction to UNIVAC’ leaflet.
(9) JUMP TO OPERATION 1 . Remington Rand UNIVAC advertising film from
(10) READ-ITEM B ; IF END OF DATA GO TO OPERATION 12 . 1950-2.
(11) JUMP TO OPERATION 1 . Notes from the 1954 MIT special program on
(12) SET OPERATION 9 TO GO TO OPERATION 2 . Digital Computers (see A-0 section above).
(13) JUMP TO OPERATION 2 . Bitsavers have a whole bunch of documents from
(14) TEST PRODUCT-NO (B) AGAINST ZZZZZZZZZZZZ ; IF EQUAL the early days of UNIVAC. These include operating
GO TO OPERATION 16 ; manuals, programming references, and the course
OTHERWISE GO TO OPERATION 15 . materials for an Advanced Programming Course.
(15) REWIND B . The FLOW-MATIC brochure from 1957 (includes the
(16) CLOSE-OUT FILES C ; D . FLOW-MATIC sample code above.
(17) STOP . (END)
The PRODUCT-NO and UNIT-PRICE fields would
have been defined separately, in the DIRECTORY while working on the Mark II in 1947 was tracked
section of the program. This is just the executable down to an actual bug (a moth) stuck in a relay. The
part. Let’s step through it: term “bug” had been used before in engineering, but
(0) Load in two input files (A is inventory, B is price), Hopper brought it into popularity.
and set two output files (C is priced inventory, D is A UNIVAC at US Steel in Indiana, on the other hand,
unpriced). had a bug that was in fact a fish; its cooling system,
(1) The key part: this compares the current product which used water from Lake Michigan, got its intake
number from file A with that from file B: blocked by a fish and thereby overheated.
If they match, then product 1 has a matching price,
and we go to section (5)–(9). COBOL and later
If A is greater, we go to section (10)–(13). After FLOW-MATIC came COBOL, which Hopper and
If B is greater, we go to section (2)–(4). her team designed from 1959 onwards. COBOL is still
(2)–(4) this implies that we have an unpriced product in use today, with the 2002 update including OO
(product 1, for example, exists on list A but on list B features, and the compiler GNU Cobol (formerly
the lowest number is product 2). We write it out on the OpenCOBOL) is available
unpriced file D. We then jump to (8), read in the next for Linux, with plenty of “Grace Hopper created the first
item A and return to (1). online resources
(5)–(9) Items A and B match; the product has a price. available. COBOL was operational compiler while
We write it, together with its price, on file C. Then we intended to be working on the UNIVAC project.”
read in the next item A and go back to (1). comprehensible by
(10)–(13) Item A is greater than item B. Read in the non-programmers, hence
next item B, if there is an item B, and go back to (1). its use of English-like syntax and structure. Modern
Note that the result of (5)-(9) (a matching pair) will be COBOL is still recognisably the same language, and
to read in the next A product but not the next B indeed recognisably inherits from FLOW-MATIC. (The
product, so this balances that out. If we have run out first COBOL compiler was itself written in FLOW-
of B data, we rewrite (9) so that all the rest of the MATIC, and was the first compiler to be written in a
products go directly to the unpriced output file. high-level language.)
(14)-(16): close the output files and/or rewind input Grace Hopper moved back into the Navy in the late
file B; stop the program. 1960s. She was on active duty for several years
So this would generate a list of priced items with beyond mandatory retirement with special approval of
their prices, and a list of unpriced items. As you can Congress, eventually retiring in 1986, at the age of 79,
see, FLOW-MATIC was squarely aimed at the as a Rear Admiral. She continued to lecture widely on
business market. early computing and other aspects of user-friendly
computing until she died in 1992.
When is a bug not a bug?
Juliet Kemp is a scary polymath, and is the author of
Famously, Grace Hopper popularised the term
O’Reilly’s Linux System Administration Recipes.
“debugging” about computer programs, after an error

www.linuxvoice.com 85
TUTORIAL KDE

THE AWESOMELY EPIC
TUTORIAL
GUIDE TO KDE
Everything you ever wanted to know about KDE (but were too
GRAHAM MORRISON afraid of the number of possible solutions to ask).

D
esktops on Linux. They’re a concept has been quietly growing more brilliant over the last
WHY DO THIS? completely alien to users of other operating couple of years, and secondly, because KDE should
• Make your desktop look systems because they never having to think be the first choice for users unhappy with their old
the way you want it to
look, not the developer. about them. Desktops must feel like the abstract idea desktop – in particular, Windows 8 users pining for an
• Dazzle your friends with of time to the Amondawa tribe, a thought that doesn’t interface that makes sense.
graphical glitz. have any use until you’re in a different environment. But fear not. We’re going to use a decade’s worth
• Save time with file But here it is – on Linux you don’t have to use the of KDE firefighting to bring you the definitive guide to
manager shortcuts. graphical environment lurking beneath your mouse making KDE look good and function slightly more like
cursor. You can change it for something completely how you might expect it to. We’re not going to look
different. If you don’t like windows, switch to xmonad. at KDE’s applications, other than perhaps Dolphin;
If you like full-screen apps, try Gnome. And if you’re we’re instead going to look at the functionality in the
after the most powerful and configurable point-and- desktop environment itself. And while our guinea pig
click desktop, there’s KDE. distribution is going to be Mageia 4, as found on this
KDE is wonderful, as they all are in their own way. month’s DVD, this guide will be equally applicable
But in our opinion, KDE in particular suffers from poor to any recent KDE desktop running from almost
default configuration and a rather allusive learning any distribution, so don’t let the default Mageia
curve. This is doubly frustrating, firstly because it background put you off.

1 FONTS
A great first target for getting your system looking isn’t a problem any more. But it’s still worth finding
good is its selection of fonts. It used to be the case a font you prefer, as there are now so many great
that many of us would routinely copy fonts across alternatives to choose between.
Most distributions don’t
include decent fonts. But from a Windows installation, getting the professional The best source of free fonts we’ve found is
KDE enables you to quickly Ariel and Helvetica font rendering that was missing www.fontsquirrel.com – it hosts the Roboto, Roboto
install new ones and apply from Linux at the time. But thanks to generic quality Slab (Hello!) and Roboto Condensed (Hello!) typefaces
them to your desktop. fonts such as DejaVu and Nimbus Sans/Roman, this used throughout this magazine, and also on the
Nexus 5 smartphone (Roboto was developed for use
in the Ice Cream Sandwich version of the Android
mobile operating system).
TrueType fonts, with their .ttf file extensions, are
incredibly easy to install from KDE. Download the zip
file, right-click and select something from the Extract
menu. Now all you need to do is drag a selection
across the TrueType fonts you want to install and
select ‘Install’ from the right-click Actions menu. KDE
will take care of the rest.
Another brilliant thing about KDE is that you can
change all the fonts at once. Open the System
Settings panel and click on Application Appearances,
followed by the fonts tab, and click on Adjust All Fonts.
Now just select a font from the requester. Most KDE
applications will update with your choice immediately,
while other applications, such as Firefox, will require
a restart. Either way, it’s a quick and effective way
of experimenting with your desktop’s usability and
appearance. We’d recommend either Open Sans or
the thinner Aller fonts.

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KDE TUTORIAL

2 EYE CANDY
One of KDE’s most secret features is that Remove the blue glow and
backgrounds can be dynamic. We don’t find much use change a few of the display
options, and KDE starts
for this when it comes to the desktops that tells us the
to look pretty good in our
weather outside the window, but we do like opinion.
backgrounds that dynamically grab images from the
internet. With most distributions you’ll need to install
something for this to work. Just search for plasma-
wallpaper in your distribution’s package manager. Our
favourite is plasma-wallpaper-potd, as this installs
easy access to update-able wallpaper images from a
variety of sources.
Changing a desktop background is easy with KDE, Alternatively, if you’d like active windows to have a
but it’s not intuitive. Mageia, for example, defaults to more pronounced shadow, change the inner and outer
using ‘Folder’ view, as this is closer to the traditional colours to black.
desktop where files from the Desktop folder in your You may have seen the option to download
home directory are displayed on the background, and wallpapers, for example, from within a KDE window,
the whole desktop works like a file manager. Right- and you can see this now by clicking on the Get New
click and select ‘Folder Settings’ if this is the view Decorations button. Themes are subjective, but our
you’re using. Alternatively, KDE defaults to ‘Desktop’, favourite combination is currently the Chrome window
where the background is clear apart from any widgets decoration (it looks identical to Google’s default theme
you add yourself, and files and folders are considered for its browser) with the Aya desktop theme. The term
links to the sources. The menu item in this mode is ‘desktop theme’ is a bit of a misnomer, as it doesn’t
labelled Desktop Settings. The View Configuration encapsulate every setting as you might expect.
PRO TIP
panel that changes the background is the same, Instead it controls how generic desktop elements are
Move any window
however, and you need to make your changes in the rendered. The most visible of these elements is the by holding Alt and
Wallpaper drop-down menu. We’d recommend Picture launch panel, and changing the desktop theme will click+dragging the
Of The Day as the wallpaper, and the Astronomy usually have a dramatic effect on its appearance, but window with your mouse.
This also applies to the
Picture Of The Day as the image source. you’ll also notice a difference in the widgets system. KRunner dialog and the
The final graphical flourish we’d suggest is to Plasma cashew widget.
In the glow ring change the icon set that KDE uses. There’s nothing
Another default option we think is crazy is the blue wrong with the default Oxygen set, but there are better
glow that surrounds the active window. While every options. Unfortunately, this is where the ‘Get New
other desktop uses a slightly deeper drop-shadow, Themes’ download option often fails, probably
KDE’s active window looks like it’s bathed in because icon packages are large and can overwhelm
radioactive light. The solution to this lies in the default the personal storage space often reserved for projects
theme, and this can be changed by going to KDE’s like these. We’d suggest going to kde-look.org and
System Settings control panel and selecting browsing its icon collections. Open up the Icons panel
Workspace Appearance. On the first page, which is from KDE’s System Settings, click on the Icons tab
labelled Window Decorations, you’ll find that Oxygen is followed by Install Theme File and point the requester
nearly always selected, and it’s this theme that at the location of the archive you just downloaded.
contains the option to change the blue glow. Just click KDE will take it from there and add the icon set to the
on the Configure Decoration button, flip to the list in the panel. Try Kotenza for a flat theme, or keep
Shadows tab and disable Active Window Glow’. an eye on Nitrux development.

3 THE PANEL
Our next target is going to be the panel at the bottom are unlocked can you re-size the panel, and even add
of the screen. This has become a little dated, new applications from the launch menu.
especially if you’re using KDE on a large or high- With widgets unlocked, click on the cashew on the
resolution display, so our first suggestion is to re-scale side of the panel followed by More Settings and select
and centre it for your screen. The key to moving Centre for panel alignment. With this enabled you can
screen components in KDE is making sure they’re re-size the panel using the sliders on either side and
unlocked, and this accomplished by right-clicking on the panel itself will always stay in the middle of your
the ‘plasma’ cashew in the top-right of the display screen. Just pretend you’re working on indentation on
where the current activity is listed. Only when widgets a word processor and you’ll get the idea. You can also

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Activities
No article on KDE would be complete without Some installations of KDE will include the
some discussion of what KDE calls Activities. Activity applet in the toolbar. Its red, blue
In many ways, Activities are a solution waiting and green dots can be clicked on to open
for a problem. They’re meta-virtual desktops the activity manager, or you can click on the
that allow you to group desktop configuration Plasma cashew in the top-right and select
and applications together. You may have an Activities. This will open the bar at the bottom
activity for photo editing, for example, or one of the screen, which lists activities installed
for working and another for the internet. If and primed on your system. Clicking on any
you’ve got a touchscreen laptop, activities will switch between them; as will pressing the
could be used to switch between an Android- meta key (usually the Windows key) and Tab.
style app launcher (the Search and Launch We’d suggest that finding a fast way to
Activities let you quickly switch between
mode from the Desktop Settings panel), and switch between activities, such as with a
different desktop modes, such as the search
the regular desktop mode. We use a single keyboard shortcut or with the Activity Bar
and launch mode, which is ideal for tablets.
activity as a default for screenshots, for widget is the key to using them more. With
instance, while another activity switches the Activity Manager open, clicking on Create
everything to the file manager desktop mode. Activity lets you either clone the current applications to the desktop for your current
But the truth is that you have to understand desktop, add a blank desktop or create a setup. To remove an activity, switch to
what they are before you can find a way of new activity from a list of templates. Clone another one and press the Stop and Delete
using them. works well if you want to add some default buttons from the Activity Manager.

change its height when the sliders are visible by clicking on the Virtual Desktops tabs and changing
dragging the central height widget, and to the left of the number of rows to ‘1’.
this, you can drag the panel to a different edge on your Finally, there’s the launch menu. Mageia has
screen. The top edge works quite well, but many of switched this from the new style of application
KDE’s applets don’t work well when stacked vertically launcher to the old style originally seen in Microsoft
on the left or right edges of the display. Windows. We prefer the former because of its search
There are two different kinds of task manager field, but the two can be switched by right-clicking the
applets that come with KDE. The default displays each icon and selecting the Switch To… menu option.
running application as a title bar in the panel, but this If you find the hover-select action of this mode
takes up quite a bit of space. The alternative task annoying, where moving the mouse over one of the
manager displays only the icon of the application, categories automatically selects it, you can disable it
PRO TIP
which we think is much more useful. Mageia defaults by right-clicking on the launcher, selecting Launcher
Spacers can be added to
your panel so that icons
to the icon version, but most others – and KDE itself Settings from the menu and disabling ‘Switch Tabs On
don’t push up against – prefer the title bar applet. To change this, click on the Hover’ from the General settings page. It’s worth
one another. This is great cashew again and hover over the old applet so that the reiterating that many of these menu options are only
for separating quick
launchers from the task
‘X’ appears, then click on this ‘X’ to remove the applet available when widgets are unlocked, so don’t despair
manager. from the panel. Now click on Add Widgets, find the two if you don’t see the correct menu entry at first.
task managers and drag the icon version on to your
panel. You can re-arrange any other applets in this
mode by dragging them to the left and right.

More sensible defaults
By default, the Icon-Only task manager will only display
icons for tasks running on the current desktop, which
we think is counterintuitive, as it’s more convenient to
see all of the applications you may have running and
to quickly switch between whatever desktops on
which they may be running with a simple click. To
change this behaviour, right-click on the applet and
select the Settings menu option and the Behaviour tab
in the next window. Deselect ‘Only Show Tasks From
The Current Desktop’, and perhaps ‘Only Show Tasks
From The Current Activity’ if you use KDE’s activities.
Another alteration we like to make is to reconfigure
the virtual desktops applet from showing four
desktops as a 2x2, which doesn’t look too good on a
small panel, to 4x1. This can be done by right-clicking We’d recommend reducing the size and centrally scaling
on the applet, selecting Pager Settings and then the KDE launch panel.

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4 UPGRADED LAUNCH MENU
You may want to look into replacing the default KRunner isn’t a great
launch menu entirely. If you open the Add Widgets name, but it’s one of the
view, for instance, and search for menus, you’ll see most powerful parts of the
several results. Our current favourite is called KDE desktop, doing away
Application Launcher (QML). It provides the same kind with almost every other
element of the GUI.
of functionality as the default menu, but has a cleaner
interface after you’ve enlarged the initial window. But if
we’re being honest, we don’t use the launcher that
much. We prefer to do most launching through
KRunner, which is the seemingly simple requester that
appears when you hold Alt+F2.
KRunner is better than the default launcher,
because you can type this shortcut from anywhere,
regardless of which applications are running or where
your mouse is located. When you start to type the
name of the application you want to run into KRunner,
you’ll see the results filtered in real time beneath the
entry field – press Enter to launch the top choice.

More than just a launcher
KRunner is capable of so much more. You can type in
calculations like =sin(90), for example, and see the
result in real time. You can search Google with gg: or
Wikipedia with wp: followed by the search terms, and
add many other operations through installable
modules. To make best use of this awesome KDE
feature, make sure you’ve got the plasma-addons
package installed, and search for runner on your
distribution’s package manager. When you next
launch KRunner and click on the tool icon to the left of
the search bar, you’ll see a wide variety of plugins that
can do all kinds of things with the text you type in. In
classic KDE style, many don’t include instructions on
how to use them, so here’s our breakdown of the most
useful things you can do with KRunner:

The 11 most useful KRunner commands
kill <process> Terminate the selected process.
#<command Open the man page for the command.
<argument> Open a website, app or document.
file:/ Launch Dolphin on the root directory.
smb://<share> Open a Samba share in Dolphin.
sftp://<SSH site> Open an SFTP folder in Dolphin.
vnc://<server:1> Access a remote desktop.
desktop 2 Switch to desktop 2.
window <app> List and switch between windows.
<name@server> Send an email to name@server.
=solve(x-20=9) Solve equations plus many other functions.

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5 FILE MANAGEMENT
File management may not be the most exciting
subject in Linux, but it is one we all seem to spend a
lot of time doing, whether that’s moving a download
into a better folder, or copying photos from a camera.
The old file manager, Konqueror, was one of the best
reasons for using KDE in the first place, and while
Konqueror has been superseded by Dolphin in KDE
PRO TIP 4.x, it’s still knocking around – even if it is labelled a
Use your mouse wheel web browser.
on KDE’s desktop
background to switch If you open Konqueror and enter the URL as file:/,
between desktops. it turns back into that file manager of old, with many
of its best features intact. You can click on the lower
status bar, for example, and split the view vertically or
horizontally, into other views. You can fill the view with
proportionally sized blocks by selecting Preview File Konqueror may be vanquished, but many of its best
Size View from the right-click menu, and preview many features have made it into the Dolphin file manager.
other file types without ever leaving Konqueror.
view, for instance, albeit one only once, and only
Click control horizontally, from the toolbar. You can also view lots
Mageia uses a double-click for most options, whereas of metadata. Select the Details View and right-click
we prefer a single click. This can be changed from on the column headings for the files, and you can
the System-Settings panel by opening Input Devices, add columns that list the word counts in text files,
clicking on Mouse and enabling ‘Single-click To Open or an image’s size and orientation, or the artist, title
Files And Folders’. If you’ve become used to Apple’s and duration of an audio file, all from within the
reverse scroll, you’ll also find an option here to reverse contents of the data. This is KDE’s semantic desktop
the scroll direction on Linux. in action, and it’s been growing in functionality for the
Konqueror is a great application, but it hasn’t been last couple of years. Apple’s OS X, for example, has
a focus of KDE development for a considerable period only just started pushing its ability to tag files and
of time. Dolphin has replaced it, and while this is a applications – we’ve been able to do this from KDE
much simplified file manager, it does inherit some for a long time. We don’t know any other desktop that
of Konqueror’s best features. You can still split the comes close to providing that level of control.

6 WINDOW MANAGEMENT
KDE has a comprehensive set of windowing functions
as well as graphical effects. They’re all part of the
window manager, KWin, rather than the desktop,
which is what we’ve been dealing with so far. It’s the
window manager’s job to handle the positioning,
moving and rendering of your windows, which is why
they can be replaced without switching the whole
desktop. You might want to try KWin on the RazorQt
desktop, for example, to get the best of both the
minimal environment RazorQt offers and the power of
KDE’s window manager. KDE is perhaps the best desktop for people who run
The easiest way to get to KWin’s configuration applications as windows, rather than full screen.
settings is to right-click on the title bar of any window
(this is usually the most visible element of any window to include All Other Desktops in the Filter Windows
manager), and select Window Manager Settings from By section, as that will allow you to quickly switch
the More Actions menu. to applications running on other desktops. We also
The Task Switcher is the tool that appears when like the Cover Switch visualisation rather than the
you press Alt+Tab, and continually pressing those two Thumbnails view, and you can even configure the
keys will switch between all running applications on perceived distance of the windows by clicking on the
the current desktop. You can also use cursor keys to toolbar icon.
move left and right through the list. These settings The next page on the window manager control
are mostly sensibly configured, but you may want module handles what happens at the edges of your

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screen. At the very least, we prefer to enable Switch of all your virtual desktops, any of which can be
Desktop On Edge by selecting Only When Moving chosen with a click.
Windows from the drop-down list. This means that Two pages down in the configuration module,
when you drag a window to one edge, the virtual there’s a page called Focus. This is an old idea where
desktop will switch beneath, effectively dragging the you can change whether a window becomes active
window on to a new virtual desktop. when you click on it, or when you roll your mouse
The great thing about enabling this only for dragged cursor over it. KDE adds another twist to this by
windows is that it doesn’t interfere with KDE’s providing a slider that progresses from click to a strict
fantastic window snapping feature. When you drag hover policy, where the window under the cursor
a window close to the left or right edge, for instance, always becomes active. We prefer to use one of the
KDE displays a ghosted window where your window middle options – Focus Follows Mouse – as this
will snap to if you release the mouse. This is a great chooses the most obvious window to activate for us
way of turning KDE into a tiling window manager, without making too many mistakes, and it means we
where you can easily have two windows split down seldom click to focus. We also reduce the focus delay
the middle of the screen area. Moving a window into to 200ms, but this will depend on how you feel about
any of the corners will also give you the ability to the feature after using it for a while.
neatly arrange your windows to occupy a quarter of KDE has so many features, many of which only
the screen, which is ideal for large displays. come to light when you start to use the desktop. It
really is a case of developers often adding things
Bird’s-eye view and then telling no one. But we feel KDE is worth the
We also enable a mode similar to Mission Control on effort, and unlikely some other desktops, is unlikely to
OS X when the cursor is in the region of the top-left change too much in the transition from 4.x to 5. That
corner of the screen. On the screen edge layout, click means the time you spend learning how to use KDE
on the dot in the top-right of the screen (or any other now is an investment. Dive in!.
point you’d prefer) and select Desktop Grid from the
drop-down menu that appears. Now when you move Graham Morrison is the editor and only KDE user on the
Linux Voice team. He likes weird synthesizers.
to the top-right of your display, you’ll get an overview

Visual effects

There’s a wide variety of visual effects in KDE, all of dependent on your graphics hardware: although should also enable the ‘Suspend Desktop Effects
which can be enabled from the Desktop Effects most devices now offer accelerated OpenGL, the For Fullscreen Windows’ option to maximise
section of the Window Manager Settings dialog. For option can be selected from the Advanced page of performance. Here’s a selection of our favourite
many of them to work, however, you’ll need to be the Desktop Effects configuration panel. If you run desktop effects, some of which have a functional
using the OpenGL compositing type. This is 3D games or other 3D full-screen applications, you reason to exist:

Translucency: The window you’re dragging becomes Magic Lamp: When minimising/maximising windows Dim Inactive: Windows that aren’t currently active
partly translucent. Options can be used to adjust the window will stretch and zoom into the toolbar. will go slightly dimmer. We prefer to lessen this
for any kind of window and element. It’s useful for checking up on your minimised apps. effect to a strength of 5 from the Tools page.

Zoom: Hold down the system meta key (usually the Present Windows: This effect works in a similar Wobbly Windows: OK, there’s no functional reason
Windows one) and press plus or minus to zoom the way to Apple’s Expose. Press Ctrl+F10 to display to enable this other than the endorphin released by
desktop around the cursor. thumbnails of all running desktop applications. contentment. Use the options to change the amount.

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TUTORIAL UEFI

UEFI BOOTING BOOT
TUTORIAL
CAMP (REBOOTED)
Upgrade your the way your system boots without installing a
GRAHAM MORRISON
distribution or resorting to Grub.

W
e’ve been using the BIOS for decades. It’s to install another operating system. In reality, the
as perennial as your keyboard and mouse, Secure Boot cataclysm has yet to materialise, as
breathing life into inert hardware when a many PCs still include a traditional BIOS or allow
little electricity is applied. These days, the POST status you to disable Secure Boot. The latter option should
messages delivered after your BIOS initialises the always be available, and you’ll need to disable Secure
system race across the screen so quickly you seldom Boot unless you want to start dealing with signing a
get the chance to read the text, making entering bootloader shim.
the BIOS itself a mad keyboard-bashing mini-game
that more often than not ends with Grub than the Muddy waters
configuration menus you’re after. Modern PCs aren’t Another potentially confusing option is something
well suited to the old-school charm of the BIOS. They called the Compatibility Support Module. To the user,
don’t want to wait for permission, they don’t want low- this will appear as a hybrid between UEFI and the
res large white fonts on a blue background. They just BIOS, a magical panacea that seems to allow us to
want to get on with the job at hand, and that’s booting forget about UEFI and BIOS completely. You’ll typically
your computer. see its effects from your computer’s own boot device
And so the BIOS is being wheeled out, albeit slowly, selection menu, usually the one you get when you
while its replacement makes itself comfortable. hold F12 after turning on your machine. What’s not
Initially developed by Intel, the booting heir was called always made clear is that the mode you boot into
the EFI – the Extensible Firmware Interface. But it’s from this point will affect how your Linux distribution
now better know as UEFI. The U is for unified, because installs itself, which in turn affects whether you’ll be
it’s not just Intel anymore. UEFI has been hanging over able to boot Linux from a UEFI boot. An installer won’t
the Linux boot system like the Sword of Damocles, install a UEFI bootloader, for instance, unless you boot
threatening to upend the booting status quo and into UEFI mode. And if your install medium doesn’t
exclude us from installing our own operating systems, support a UEFI bootloader, you’re stuck.
thanks to the spectre of Secure Boot. Secure Boot is But defaulting to a UEFI installation and forgetting
a system that embeds a key without your firmware about the BIOS and the Compatibility Support Module
so that only operating systems signed by the key is beginning to make more sense. Modern laptops
are allowed to boot. It’s primarily a way for Microsoft are often pre-configured to boot UEFI, and there will
– in part, legitimately – to ensure nothing has been be a time when falling back to the BIOS won’t be an
tampered with from the very first moment your PC option. But these days, there’s nothing to be scared
gets power to the moment you get to play with the of, and in many ways, UEFI can make the whole
inspirational Windows 8.1 interface. But it could booting process more transparent. The bootloaders
also make life harder for when you do intentionally may, at the moment, feel slightly more primitive that
want to tamper with your PC by making the choice their well worn BIOS equivalents, but to us the boot
process actually makes more sense than the black
arts involved in the old methods. If you’ve spent the
last decade thinking about booting in terms of MBR
bootloaders, Grub and old-style partitions, get ready to
update your notes.
We’re going to create our own UEFI boot
environment, and we’ll be doing this primarily from
the Mint Live desktop as found on last month’s DVD,
in much the same way you might fix a broken MBR
installation or reconfigure Grub. You can use any
similar distribution, however, as there’s nothing Mint-
It doesn’t look much, specific about our instructions. We’re also going to
but this is the Refind use a 1GB USB stick to get around the limitation of
bootloader running from BIOS-only booting DVD drives, but we’ll only use this to
our new EFI partition. ‘fix’ the installation, rather than initiate it.

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The system we create won’t be perfect. It won’t Depending on which boot
handle distribution updates to the kernel without a option you take, your
little further tinkering, and you’ll need to make plenty system will boot into either
of considerations for your own hardware rather than UEFI or BIOS boot modes.
these instructions for ours. But you will learn how
UEFI works from a practical perspective, and learn
how to troubleshoot the future of Linux booting.

Look into the black box
The great thing about taking control of UEFI yourself
is that you don’t have the problem of which mode
your system has booted from – UEFI or BIOS, which
is especially useful if you’re booting off a DVD that can
only boot in the old BIOS mode. When you get one
distribution running , it’s easy to add more, and it can
also be the only way of running the latest Microsoft
Windows or even Apple’s OS X alongside.
Mint 16 and many other distributions have their
own preliminary support for UEFI bootloaders, as and you’ll find it in Mint 16’s Administration menu. It’s
long as you’ve booted into the correct boot mode, an application that hides a lot of power. In the top-right
but we’ve found its approach a little unpredictable, you’ll find a drop-down list of all the drives detected
along with many other distributions. We had similar and connected to your system. When you select one
problems with Mageia, for example. Which is why of these drives, the horizontal bar beneath the menu
we want to roll our own – the intention being to will become populated with a graphical representation
learn more about how it works and how you might of the partitions on that drive. Each partition is a self-
approach installation with a distribution that doesn’t contained horizontal block and its border colour is
support UEFI. And the real trick isn’t installing the used to show the filesystem used for each partition.
distribution, it’s configuring your drive in such a way Within each partition, a yellow bar is used to indicate
that it works with UEFI. The most important part is how much space is taken up by data, with white used
booting to a Live distribution, to indicate free space on the partition. This is handy if
But before we get to the booting part, we need to you want to use free space to resize a partition.
start with partitioning. To boot UEFI, need to use a
different partitioning scheme. So you’ll need a spare Danger: partitioning!
drive – or one you’re willing to sacrifice, as all the Make sure you select the correct drive from the
PRO TIP
data it contains will be removed in the process, and drop-down list. If you’ve only got one drive installed,
If you’re installing Linux
you’ll need to be confident about your current drive this isn’t going to be a problem. If you’ve got five, you
alongside Windows, make
configuration. We’re going to be reformatting the drive need to be certain the drive you’re selecting is the one sure you disable Fast
and you don’t want to overwrite or repartition personal you intend to partition for a UEFI bootloader, because Startup and Secure Boot.
data in the process of experimentation, so it may even you’re going to remove all the data on the drive in the
be wise to disconnect any other drives. With all that in process. Our drive, for example, already has a Linux
mind, locate your nearest Linux live CD and USB stick partition on it, but this is going to disappear in the very
and boot your machine. next paragraph – you have been warned.
There’s nothing wrong with the command line, The old partitioning scheme used a table to store
but when it comes to partitioning drives, we like the the partition data, and this table was stored on the
visual safety net provided by GParted. Fortunately, this Master Boot Record (MBR), a statically located 512
essential application is part of most live distributions, bytes allocated to explain the layout of a drive to
the BIOS. Nearly all Linux drives prior to UEFI used
MBR, and MBR can still be used in some cases with
UEFI. But it’s better to make clean break. The first
thing we need to do with our drive is create a new
partition table.
With your drive definitely selected, click on a
partition on the drive and select Device > Create
Partition Table from the menu. From the dialog that
appears, click on ‘Advanced’ and while avoiding the
temptation to click on ‘amiga’, select ‘gpt’ as the
partition type followed by Apply. All the data on that
drive is effectively dead to us now, and you’ll see there
are no partitions on your drive. Just the cold grey of
You need to create a GPT partition table for UEFI booting. unallocated space.

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It’s vital that the EFI new UEFI boot scheme to your system firmware so
partition you create has that it knows there’s a new way to boot the system.
a partition type of EF00. You will need to know where your distribution
Either use cgdisk on the is installed. The easiest way of doing this is from
command line or enable GParted’s drop-down device menu, as you’ll be able to
the ‘boot’ flag for the see the device node (/dev/sda1, for instance) along
partition in GParted.
with the partition configuration and the UUID of the
device if you make a note of it.
To mount the partition, open a terminal and type
the following, replacing sda2 with the location of your
own distribution’s root partition:
sudo -s
mount /dev/sda2 /mnt/
We’re now going to create a couple of partitions to With an MBR installation, Grub uses the /boot
fill the space, but the first is mandatory. This is the folder to not only hold its configuration files, but also
EFI system partition, and it’s this that UEFI expects the kernel and filesystem image for booting. We need
to find on your drive and where it will eventually find both of these for UEFI and the UEFI partition needs
your UEFI bootloader. For that reason, it’s operating to replace /boot on the filesystem tree. Here’s the list
system-agnostic, and needs to be formatted as FAT32 of commands we used to move the old boot aside,
for maximum compatibility. It should also be a certain mount the new one and copy the files we need over
size. The UEFI standard recommends this as 512MB, (remember to replace filenames and devices with
although in execution we’ve found that 100MB ones that match your own system):
partitions work just as well. Eventually, you could cd /mnt
install Linux kernel images into this partition, so there’s mv boot boot_old
no harm in making it larger unless you’re working with mkdir boot
an expensive SSD. To create this partition, click on mount /dev/sda1 /mnt/boot
the ‘plus’ icon in the toolbar, set its size to 512MB and mkdir boot/EFI
make sure it uses the FAT32 filesystem. cp boot_old/vmlinuz-3.11.0-12-generic boot/vmlinuz
The next step is important. If you were doing this cp boot_old/initrd.img-3.11.0-12-generic boot//initrd.img
from the command line, using a tool like gdisk, you’d We now need to add the new UEFI partition as
need to mark this partition as type EF00. This tells a mount point, and to do this we need to add the
UEFI that this is the system partition (also known as partition’s unique identifier (its UUID) to the etc/ftsab
the ESP – the EFI System Partition), and it’s the one configuration file. You can get the UUID from GParted
to use for booting. GParted doesn’t use hex codes, or by typing the following:
but you still have to tell UEFI about the partition. blkid
You do this by setting the ‘boot’ flag, which is a little /dev/sda1: UUID=”BD8C-E7B3” TYPE=”vfat”
incongruous when you may be used to using a similar /dev/sda2: UUID=”0abcc4da-c2aa-437b” TYPE=”ext4”
flag in MBR systems to tell the BIOS which partition We’ve shortened the output slightly, but you can see
to boot. Right-click on the freshly created partition the UUID for the UEFI ‘vfat’ partition on the first line.
and select ‘Manage Flags’. From the list of flags that This needs to be added as a new line in etc/fstab on
appears, select ‘boot’, this should disable the default your distribution’s root partition by editing the file with
‘msftdata’ flag as well as cause some drive activity. nano etc/fstab:
With the EFI partition created, assigned a partition UUID=BD8C-E7B3 /boot/efi vfat defaults 0 2
type and formatted FAT32, we can now install the
bootloader. There are several that work with EFI – and Installing the bootloader
even Grub can be made to work with the new scheme, We can now install the bootloader itself. If we’d been
although you don’t win any house points for simplicity able to boot into the distribution using UEFI, we could
of you take that route. The two we tried for this tutorial simply install this through a package manager and
PRO TIP
were Gummiboot and Refind. Both have a couple of everything else would be handled automatically. But
GParted can create an
incompatible EFI boot
things in common. Firstly, their names are terrible. But because our system is currently booted from BIOS
partition. If this happens, they’re both straightforward to install and use a simple mode, we need to copy the files manually, edit a config
we’d recommend using directory structure on your UEFI partition plus a file and then add the bootloader to the UEFI firmware
the command line tool
cgdisk to create a EF00
configuration file to hold information on the operating by booting in UEFI mode off a USB stick.
type partition formatted systems you want to boot. We went with Refind. Let’s first download the binary version of the Refind
with fat32. We’ve now got to the point where we can install bootloader (refind-bin-0.7.7.zip) plus the image of
the UEFI bootloader, and there are two stages to the the same bootloader (refind-ﬂashdrive-0.7.7.zip)
process. The first is to mount the distribution you we’re going to use to boot off the USB stick. Both
want to add, and to now make the boot folder the can be grabbed from www.rodsbooks.com/refind
UEFI partition we just created. The second is to move via links to SourceForge. To install the bootloader, we
all the files you need to the UEFI partition and add the need to unzip it and copy the folder to the mounted

94 www.linuxvoice.com
UEFI TUTORIAL

boot partition on our distribution:
cd ~/Download
unzip refind-bin-0.7.7.zip
cd refind-bin-0.7.7/
cp -r refind /mnt/boot/EFI/
cd /mnt/boot/EFI/refind
From here you need to remove either the 32-bit
or the 64-bit bootloader, depending on what your
system is capable of, with rm refind_ia32.efi or rm
refind_x64.efi, and edit the configuration file (nano
refind.conf) to add the details about the partition that
contains the distribution you want to boot. Here’s the
contents if ours for booting Mint 16 – you should take
a look at your boot options first, to make sure you get
With Refind copied to a
any kernel options specific to your system: delete all data at that location, so get it right and make
USB stick, you will be able
resolution 1024 768 sure there’s nothing on there you want to keep. You to boot into UEFI mode and
menuentry “Mint Linux” { can now reboot your system and launch your BIOS/ select the EFI shell.
icon EFI/refind/icons/os_linuxmint.icns system boot menu. You should see the USB stick
loader vmlinuz appear as a UEFI boot source. Select this and from
initrd initrd.img the graphical boot menu that appears, choose the first
options “root=/dev/sda2 rw rootfstype=ext4 option, which should take you to the EFI shell.
add_efi_memmap”
} Welcome to your new shell
Our final challenge is to tell the UEFI firmware that The EFI shell is full of commands for adding, removing
we’ve created a new EFI partition and bootloader. Had and managing storage from the EFI bootloader.
we been able to boot into the live desktop through Before you get to the prompt itself, you’ll see how
UEFI, the firmware variables would be mounted EFI is interpreting your various filesystems and the
as part of the system, and we’d be able to add the aliases it’s giving them. For us, fs0: was the USB drive
bootloader by typing: and fs1: was the EFI partition we just created on the
sudo apt-get install efibootmgr hard drive, but these assignments will depend on your
efibootmgr -c -l \\EFI\\refind\\refind_x64.efi -L new_refind own system. From the command prompt, type fs1:
But we can’t. Instead, one solution is to create a to switch to the root folder of our new EFI partition.
USB stick with the Refind bootloaders installed, and The EFI shell is crammed full of commands to help
from there, use the EFI shell to add the bootloader you manage storage and booting. Type help if you
manually. This isn’t really what we’d recommend. want to see what it’s capable of – you can use ls,
You’re better off installing Mint through a UEFI- cp and rm, for example. But we’re only going to use
booted USB live image, but the EFI shell is much one command to add our bootloader to the system
more interesting and can be a very powerful tool if firmware. We’re assuming you don’t have any other
your system doesn’t boot. Plug in your USB stick and EFI boot loaders installed, because using one of them
use either GParted or dmesg to find for certain what would have been a much easier solution for all of this,
its device node is and type the following from the but you can check by typing bcfg boot dump -b. If
unzipped folder of the Refind flash image: you do have another installed, you’ll need to adjust the
dd if=refind-flashdrive-0.7.7.img of=/dev/sde number 1 to a free slot in the command below, which
Remember to replace /dev/sde with the location of is going to add the new bootloader to the firmware:
your own USB drive and also remember that this will bcfg boot add 1 fs1:\EFI\refind\refind_x64.efi “LV_Refind”
**bcfg instructions output
Target = 0001.
bcfg: Add Boot0001 as 1
And that ’s all there is too it. It’s been a challenge,
but when you now reboot your machine (type reset
from the EFI shell), you’ll see LV_Refind as a new EFI
boot option. Hopefully, you’ve learnt how UEFI works
and how it’s implemented, and also how you might be
able to troubleshoot UEFI problems in the future.
Adding new distributions, for instance, is now a
case of copying their kernel and filesystem images
to the partition and adding a new configuration entry.
You might also want to look into making symbolic
With Refind added to the system firmware, our boot entry links for these files for when your distribution updates
should appear from the system (press F12) boot menu. itself. Other than that, you’re ready to go.

www.linuxvoice.com 95
CODING PYTHON DRAWING

PYTHON DRAWING
TUTORIAL
PRETTY PATTERNS
Use the Python turtle to illustrate loops and recursion, and
BEN EVERARD
prove that not all art is quite useless.

T
here are some programming techniques, like
WHY DO THIS? loops and recursion, that we use all the time,
• Gain a better almost without thinking. However, sometimes
understanding
common programming it’s hard to really see what’s going on. Being able to
techniques really visualise what’s going on behind the code can
• Draw pretty pictures help you become a better programmer.
• Win a T-shirt! Python comes with a turtle module. It’s about as
simple as a drawing program can be. It enables you to
control a turtle with a pen around the screen. You can
tell it to go forwards, turn through various angles, put
the pen down or lift it up, and change its colour. In a
world where almost everything seems to have OpenGL
accelerated graphics, sometimes it’s nice to take a
step back and look at what you can create with very
little. In this tutorial, we’re going to look at how we can
build complex pictures using just this turtle module The empty handed painter from your streets is drawing
and few coding techniques. crazy patterns on your screen, with simple Python.
Let’s start really simply, and just draw a square:
import turtle draw_polygon(6,20)
jonney = turtle.Turtle() turtle.exitonclick()
for i in range(0,4): Because the turtle module only works in whole
jonney.forward(100) numbers, this won’t work properly for polygons where
jonney.right(90) 360/sides isn’t a whole number, but it’s good enough
turtle.exitonclick() for our purposes.
That’s all you need. Python will take care of creating
the window to display it in. For some reason this Intensify the artiness
author always feels the need to give the turtles This is an article about creating art from code, and
anthropomorphised variable names. simple polygons aren’t very attractive. With a few
You can turn this code into more general polygon tweaks, the function can be made a little more artistic:
drawing code by moving the loop into a function like import turtle
as follows: def draw_spiral(angle, length_start, length_increase, sides):
Figure 1. Recursion
import turtle for i in range(0,sides):
can quickly build up the
def draw_polygon(sides, length): jonney.forward(length_start+(i*length_increase))
number of lines in a fractal
as you go to greater for i in range(0,sides): jonney.right(angle)
depths, so it’s best to call jonney.forward(length) def draw_petals(length, number):
speed(0) to set it to the jonney.right(360/sides) for i in range(0, number):
fastest speed. jonney = turtle.Turtle() jonney.forward(length)
jonney.right(180-(360/number))
jonney = turtle.Turtle()
draw_spiral(30, 10, 2, 20)
jonney.penup()
jonney.goto(0,200)
jonney.pendown()
draw_petals(50,20)
turtle.exitonclick()
You can also vary the colour through the loops. This
both helps you see how the images are drawn, and
makes the outcomes a little more impressive. We
changed the draw_petals() function to the following to

96 www.linuxvoice.com
PYTHON DRAWING CODING

fade the lines from blue through purple to red. The Kock snowflake
def draw_petals(length, number): was originally designed
red=0.0 by taking a triangle and
blue=1.0
placing a smaller triangle
on every edge, then a
for i in range(0, number):
smaller triangle on each
red=red + (1.0/number)
new edge, etc.
blue = blue - (1.0/number)
jonney.color(red,0.0,blue)
jonney.forward(length)
jonney.right(180-(360/number))
turtle.exitonclick()

Fractals and recursion
You can get quite artistic using loops to draw shapes,
but you can take drawing a stage further using
recursion. (Recursion is just when a function calls
itself.) You can use this to progressively process all the
data in a set, or to draw pretty pictures.
This might sound a little strange if you’ve never jonney.forward(length)
thought of trying to draw with code, but actually, else:
recursion is a really versatile tool in the coder-artist’s draw_fractal(length, depth-1)
toolbox, and it’s all thanks to a mathematical trick jonney.left(120)
called fractals. if depth == 1:
The idea is really simple. You take a simple line jonney.forward(length)
shape like figure 1 part 1. Then you replace every line else:
in the shape with a copy of the lineshape. The result of draw_fractal(length, depth-1)
doing this once is figure 1 part 2. However, you can jonney.right(60)
keep doing it as many times as you like, each time you if depth == 1:
replace every line with a copy of the original line shape. jonney.forward(length)
Figure 1 part 3 shows it done a third time, but else:
assuming you had a high enough resolution display (or draw_fractal(length, depth-1)
if you kept zooming in), you could just go on repeating
this more and more times. jonney = turtle.Turtle()
The code we used to create figure 1 is: jonney.penup()
import turtle jonney.goto(-200,0)
def draw_fractal(length, depth): jonney.pendown()
if depth == 1: draw_fractal(15,1)
jonney.forward(length) turtle.exitonclick()
else: In this case, we use the depth function to limit the
draw_fractal(length, depth-1) number of times the recursion happens, otherwise it
jonney.right(60) could go on indefinitely.
if depth == 1: This particular fractal is known as a Kock curve after
its creator, Helge von Kock. However, this isn’t its
best-known form. If you use a triangle for the first
Running Python programs iteration, but revert to the line segment for every other
Python is a very easy programming language to get iteration, you get a Kock snowflake as shown above.
started in. It’s interpreted, which means you don’t This is created with the code:
need to compile the code you’ve written before you import turtle
can run it, and it’s installed by almost every def draw_snowflake(length, depth):
distribution of Linux by default. What’s more, the draw_fractal(length, depth-1)
turtle module is part of the standard Python library, jonney.left(120)
so you don’t need to install anything to run the code draw_fractal(length, depth-1)
in this article. Just enter it into a text editor, save the jonney.left(120)
file (a .py file extension is usual, but not required), draw_fractal(length, depth-1)
then run it from the command line with:
jonney = turtle.Turtle()
python filename.py
jonney.penup()
If you don’t end your code with the following, then the
window will shutdown as soon as it’s finished jonney.goto(-200,0)
running. jonney.pendown()
turtle.exitonclick() draw_snowflake(7,4)
turtle.exitonclick()

www.linuxvoice.com 97
CODING PYTHON DRAWING

It also includes the fractal() function from the
previous example.
You can use this same method of recursion in
another way. For example, you can use it to continually
add lines in a particular place. For example, you can
generate a tree by drawing a ‘Y’ shape, then continually
adding smaller ‘Y’ shapes to the end of each branch.
See right for how this works out. In part 1 to 3, the
depth is 1 to 3 respectively. Part 4 has a depth of 7.
This was generated with the code:
import turtle

def draw_tree(length, depth):
jonney.forward(length)
if depth > 1:
jonney.left(45)
draw_tree(length/2, depth-1)
jonney.left(90)
draw_tree(length/2, depth-1)
jonney.right(135)
jonney.right(180)
jonney.forward(length)

jonney = turtle.Turtle()
jonney.penup() With fractals that get smaller and smaller, you’ll quickly
jonney.goto(0,-100) reach the limit of the resolution of the screen.
jonney.pendown()
jonney.left(90) flip = 1
jonney.speed(0) for i in range (0, length2):
draw_tree(160,7) jonney.left(angle2)
jonney.forward(length1)
turtle.exitonclick() if depth > 1:
You can extend this. Instead of drawing a Y shape, jonney.left(angle1*flip)
you can expand a herring bone in the same way (see
below). Instead of creating the classic tree shape, this draw_fern(floor((length1/3)-(i/2), 1), angle1*flip,
creates a fern-like drawing. The code for this is: floor(length2-i,1), angle2*flip, depth-1)
These ferns are depths 3 import turtle jonney.left(180-angle1*flip)
and 5. We’ve spaced it out def floor(x,y): flip = flip * -1
to make it easier to see if x > y:
what’s going on, but you return x jonney.left(180)
can change the parameters return y
to create more realistic for i in range(0, length2):
plants.
def draw_fern(length1, angle1, length2, angle2, depth): jonney.forward(length1)
jonney.right(angle2)

jonney = turtle.Turtle()
jonney.penup()
jonney.goto(0,-100)
jonney.pendown()
jonney.left(90)
jonney.speed(0)
draw_fern(40,60,8,4,1)

turtle.exitonclick()
This particular code is very sensitive to the
parameters you give it. You also can customise the
fractal by changing the way the line lengths are passed
to the next level of recursion, or by progressively
increasing the angle so that the fern starts to curl
towards the end.

98 www.linuxvoice.com
PYTHON DRAWING CODING

If you’re feeling really adventurous, you could write a What we’ve covered in this tutorial may seem a bit
program that flips from the tree recursion to the fern pointless, flippant even, but we’ve used exactly the
recursion at a certain depth. You can develop fractals same programming techniques that are used in
like this using different shapes. The key is to make normal software. By learning how to exploit them to
sure that, at the end of each run of the function, you draw shapes, you hone your knowledge of how to
return the turtle to the same place it started from. structure code, and this can only make you a better
programmer whatever language you use.
Fantastic Mr Fractal There are also a few cases where fractals
There are loads of possible fractals you could draw, themselves are useful to programmers – for example,
and a quick web search will pull some up. One thing to in creating complex terrain in video games.
remember when programming fractals like the fern
and the tree is to make sure you always finish the
Ben Everard is the co-author of Learning Python with
fuction at the same physical location the turtle started Raspberry Pi, soon to be published by Wiley. He’s also pretty
it. Otherwise it’ll end up chaotic. good at turning foraged fruit into alcohol.

Competition time

You’ve seen how, by using iteration and loops, The artwork produced can be in any colour, and garish entries will be looked upon
you can create complex drawings with very category. Abstract, still life, favourably.
little code. In this competition, we’re going to impressionism, cubeism. Sculpture is jonney = turtle.Turtle()
put this to the test. The challenge is to create probably out, but otherwise, anything jonney.speed(0)
a Python program that uses the turtle module goes as long as it looks good. jonney.left(90)
to draw something. I have to be able to Up to three entries per person will be jonney.width(2)
output the code, and the winner will be the accepted. draw_tree(128,6)
person that creates what we think is the best You don’t have to buy a copy of Linux jonney.width(1)
piece of art. To put your coding skills to the Voice to be eligible. Feel free to pass on jonney.penup()
test, we’re going to give you a limit of 100 the competition details to non LV jonney.goto(210,0)
lines of Python – no more. readers, and details will be posted on for i in range(0, 10):
You may have noticed that we haven’t www.linuxvoice.com. for j in range(0,10):
really tried to keep our code short in this Turtles don’t have to be called Jonney, jonney.pendown()
tutorial and quite a few of the functions we’ve and you don’t have to limit yourself to a draw_snowflake((i+j)%3+1,2)
used can be shortened if needed. single turtle. jonney.penup()
The rules are: To give you an example of what we’re jonney.setheading(90)
Using only the turtle module, and no looking for, take a look at figure 5. This was jonney.forward(30)
more than 100 lines of Python (2 or 3, created with the following code (the jonney.setheading(270)
your choice), you must draw a picture. functions for the tree() and snowflake() as as jonney.forward(300)
You may use any of the techniques here, they’re given earlier in the tutorial, and not jonney.setheading(180)
or any others you invent, copy, steal or repeated here, though if you wish to use them jonney.forward(50)
otherwise come across. in your example, you WILL have to include turtle.exitonclick()
The only module you can use is the turtle them in your 100 lines). Although this picture Good luck, have fun, and remember that while
module. Any other import lines will be doesn’t make it look like it, the judge does like good artists borrow, great artisits steal!
deleted.
Pictures will be judged on artistic merit.
The judge’s decision is final.
Lines of comments are allowed (and
encouraged) and won’t be included in the
100 line count. Feel free to add
information to your program, and all
programs must be licenced under an OSI
approved open source licence. Preferably
the GPLv3, though you can use a
different one should you so choose.
In order to enter, send your entries to
ben@linuxvoice.com by 1 May 2014.
The winner will receive an exclusive
Linux Voice competition winner’s T-shirt.
These are not, and will not, be available
in the shops. The only way to get one is
to submit a winning entry to a Linux It may be spring now, but the long, dark winter is still vivid in our memories. Help us forget
Voice competition. it with some uplifting artwork, and give yourself the opportunity to win clothing!

www.linuxvoice.com 99
CODING CONCEPTS

KEY EXCHANGE: THE
TUTORIAL
SCIENCE OF SECURITY
Maths and physics – two ways of keeping your data
BEN EVERARD
safe. Read on, bold explorer…

W
e’re used to thinking of secure exchange algorithm, which doesn’t use public keys.
WHY DO THIS? communications in terms of encryption. If There’s no long-term data that could be compromised
• Understand advanced an attacker can’t crack the encryption then that could be used to decrypt past data wholesale.
cyptography techniques.
they can’t get into the data, right? Wrong. The
• Beat GCHQ (and the CIA
as well). encryption method is only one of the many parts that Perfect security
• Gives you an excuse make up a secure exchange. The Diffie-Hellman algorithm involves three parts that
to use the laser beams One chink in the electronic armour is the key are combined to make the key. It also needs a method
that you’re stuck to your exchange. That is, the process by which the two of combining them that is a form of encryption, which
sharks’ heads.
parties decide on which key to use for the symmetric has the basic property that (s + a) + b is the same as
encryption. They both have to know the key, so this (s + b) + a. The ‘+’ symbol is used here generically to
has to travel between them in order to communicate. mean any secure form of combination. By secure, we
However, an attacker may be listening in, and the key mean that if you know s and (s+a), you can’t use that
has to be sent in such a way as to stop them being to work out a.
able to find it out. If Alice wants to communicate with Bob, and GCHQ
The simplest way to agree on a key is to use public are trying to listen in, Alice starts by sending Bob a
key cryptography. In this, one party can simply random number that we’ll call s. This is sent in plain
generate a symmetric key, encrypt it with the other’s text, so everyone can read it. Then, both Alice and Bob
public key, and send it. Then both parties can make up their own random numbers. We’ll call these a
communicate using the symmetric key. and b respectively. They don’t send them, but combine
It’s a very simple method, and it works fine. Anyone them with s first. Alice then sends (s + a) to Bob, and
who intercepts the message won’t be able to read it Bob replies with (s + b).
because they don’t have the private key to decrypt the Now they have these, Alice can calculate (s + a) + b,
message. The only flaw is the fact that the symmetric while Bob can calculate (s + b) + a. As we’ve said,
keys are used over a long period of time, and if one is these are equal, so they’re used as the symmetric key.
compromised once, all previous messages can be GCHQ knows a, (s + a) and (s + b) , but has no way
decrypted. This is a particular problem when of calculating (s + a) + b provided we have picked a
GCHQ can listen in on organisations like GCHQ and the NSA are intercepting suitably secure method for combining the numbers.
steps 1, 2 and 3, but they and storing huge amounts of data. As with all encryption methods, if a suitably powerful
won’t be able to find out Stopping this is known as Perfect Forward Secrecy computer could be found, then it would be possible to
the key. (or PFS), and is possible using the Diffie-Hellman key subject this to a brute-force to find the key. However,
this would have to be done separately for each run of
Diffie-Hellman rather than just once, making it a far
Step 1: p=23, g=18 less attractive proposition.
The method that Diffie and Hellman used to
Step 2 : (g mod p) = 9 combine s, a and b is the fact that for a prime number
(p), and a primitive root (g), (g mod p) mod p = (g
Step 3: (g mod p) = 6 mod p) mod b. Therefore, both p and g are sent in
plain text first, then (s + a) was g mod p and (s + b)
was g mod p.

A quantum of security
Diffie-Hellman requires us to have a method of
combining the numbers that can’t be broken. While
there are several options with no known weaknesses,
Alice Bob
it’s possible that a way will be found to decompose
a=7 b=10
the messages (s + a) and (s + b), and this would allow
Step 4: 9 mod 23 = 4 Step 4: 6 mod 23 = 4
an attacker to break the encryption.
Key = 4 Key = 4
Instead of relying on mathematical properties to
allow you to transmit the data securely, you could rely

100 www.linuxvoice.com
CONCEPTS CODING

on physical properties. If our key exchange is
protected by the laws of physics, we can be far more Public and symmetric key encryption
confident that GCHQ isn’t listening in.
This is possible using the Quantum Key Distribution There are two different types of encryption), there is just one key to
algorithm. In this method, each bit of information is encryption: public key and symmetric encrypt and decrypt the message.
key. In public key encryption, everyone Symmetric key encryption is
encoded as a single photon sent from Alice to Bob.
has two keys, one public, one private. much faster the public key, and so is
The data is in the polarisation. If you think of the light
The public key is made public, while used for almost all purposes except
wave travelling through space, the wave could be the private key is known only to that authentication. SSH, for example,
moving up and down, side to side, or at any other user. When someone wants to send will use public key encryption to
orientation. This orientation of the wave is its data to the user, they can encrypt it make sure that the server you’re
polarisation with the public key, and then it’s only communicating with is really who it
It is possible to measure the polarisation, but not decryptable with the private key. says it is, and once that’s done it will
precisely. Because of quantum indeterminacy, you In symmetric key encryption negotiate a symmetric key using one
can only measure it against two perpendicular axes. (sometimes known as private key of these key distribution algorithms.
For example, if you set your axes as vertical and
horizontal (0 and 90 degrees), and a photon is
polarised at 0 degrees, you’ll get a reading as vertical, 90 is 1. She then sends a series of 0s and 1s with
and likewise for a horizontal photon. However, if a photons and switches between vertical and diagonal
photon has a polarisation of 45 degrees, there’s a 50% at random.
chance you’ll get a reading of vertical and a 50% Bob has receiving equipment that he can set up at
chance of horizontal. vertical and diagonal orientations as well. However, if
What’s more, by reading the state of the photon, you he is set up vertical while Alice is set up diagonal, he
destroy it. will receive the photon incorrectly, and likewise if he is
Using these two properties, Charles Bennet and diagonal and Alice is vertical. As Alice sends her
Gilles Brassard developed a system to send a key so stream of ones and zeros, Bob also randomly
that it can’t be intercepted. Again, we’ll look at an changes between vertical and diagonal.
example where Alice sends a key to Bob and GCHQ
tries to listen in. Keep GCHQ in the dark
Alice has a photon transmitter that can send After Alice has sent a long enough string of bits, she
polarised photons in four different orientations: 0 sends Bob a list of what orientations she was using
degrees, 45 degrees, 90 degrees and 135 degrees. for which bits. Bob compares this to how he had his
These are in two groups: 0 and 90 are vertical, while receiving equipment set up. On average, they should
45 and 135 are diagonal. For each photon, she have had the same
randomly selects to use either vertical or diagonal. In
vertical, 0 degrees represents a binary 0 and 90
orientation for half of the
bits, so Bob replies by “Quantum Key Distribution
degrees represents a binary 1. In diagonal, 45 is 0 and saying which bits he was
sounds fanciful, but there are
already some implementations.”
correctly set up for. Both of
these messages can go
unencrypted since they are
no use to an attacker. Alice and Bob can then use the
values of bits that Bob received correctly as the key.
GCHQ can’t intercept the photons since they don’t
know what orientation Alice is as she sends them.
For example, If Alice is vertical, and GCHQ intercept
the photon, they have to guess between vertical and
diagonal. If they are diagonal, then there’s a 50%
chance that they will read it incorrectly. In reading in,
they destroy the original photon, so they have to
create a new one to send to Bob. They have no way of
knowing if they read the original one correctly, so they
can’t be sure either what value it is or what orientation
Alice was in. They may get lucky on a few photons,
but if they’re building up a key of 512 bits, then the
errors will quickly mount up.
This might sound fanciful, but there are already
some implementations, and April 2014 marks the
To see if you’re using PFS, look at the technical details tenth anniversary of the first bank transfer protected
of the certificate. If you see ECDHE (Eliptic Curve Diffie by Quantum Key Distribution (see www.secoqc.net/
Hellman Ephemeral) or DHE (Diffie Hellman Ephemeral), downloads/pressrelease/Banktransfer_english.pdf
then you have perfect forward security. for details).

www.linuxvoice.com 101
CODING KERNEL

LINUX KERNEL:
TUTORIAL
YOUR FIRST MODULE
VALENTINE Ever wanted to start hacking the kernel? Don’t have a
SINITSYN clue how to begin? Let us show you how it’s done…

K
ernel programming is often seen as a black
WHY DO THIS? magic. In Arthur C Clarke’s sense, it probably
• Understand the common is. The Linux kernel is quite different from its
features shared by all
kernel modules. user space: many abstractions are waived, and you
• Earn brownie points in have to take extra care, as a bug in you code affects
job interviews. the whole system. There is no easy way to do
• Tinker with the floating-point maths, the stack is fixed and small, and
foundations of your the code you write is always asynchronous so you
Linux machine.
need to think about the concurrency. Despite all of this
though, the Linux kernel is just a very large and
complex C program that is open for everyone to read,
learn and improve, and you too can be a part of it.
Probably the easiest way to start kernel
programming is to write a module – a piece of code
that can be dynamically loaded into the kernel and LXR (Linux Cross Reference) is a web-based system for
navigating Linux sources (and other large codebases).
removed from it. There are limits to what modules can
do – for example, they can’t add or remove fields to
common data structures like process descriptors. But implement it at the kernel level as well. A word of
in all other ways they are full-fledged kernel-level code, warning before we start: a bug in your module may
and they can always be compiled into the kernel (thus lead to a system crash and (unlikely, but possible)
removing all the restrictions) if needed. It is fully data loss. Be sure you’ve backed up all your important
possible to develop and compile a module outside the data before you start, or, even better, experiment in a
Linux source tree (this is unsurprisingly called an virtual machine.
out-of-tree build), which is very convenient if you just
want to play a bit and do not wish to submit your A module’s anatomy
changes for inclusion into the mainline kernel. As most of the Linux kernel modules are written in C.
In this tutorial, we’ll develop a simple kernel module (apart from low-level architecture-specific parts), it is
that creates a /dev/reverse device. A string written to recommended that you keep your module in a single
this device is read back with the word order reversed file (say, reverse.c). To begin, let’s include some
(“Hello World” becomes “World Hello”). It is a popular common headers and describe the module using
programmer interview puzzle, and you are likely to get predefined macros:
some bonus points when you show the ability to #include <linux/init.h>
#include <linux/kernel.h>

The environment #include <linux/module.h>

To develop kernel code, you’ll need a decent text MODULE_LICENSE(“GPL”);
editor. Choosing one is actually a matter of taste, MODULE_AUTHOR(“Valentine Sinitsyn <valentine.sinitsyn@
however many kernel developers tend to use either gmail.com>”);
Vim or Emacs, and Linus prefers his own flavor of MODULE_DESCRIPTION(“In-kernel phrase reverser”);
the MicroEMACS editor. If you prefer IDEs (although Everything is straightforward here, except for
they aren’t very useful for kernel development), you MODULE_LICENSE(): it is not a mere marker. The
can easily google for recommendations how to setup kernel strongly favours GPL-compatible code, so if you
Eclipse CDT. set the licence to something non GPL-compatible
Regardless the editor you chose, your code
(say, “Proprietary”), certain kernel functions will not be
should always follow Linux Coding Style guidelines
available to your module.
(Documentation/CodingStyle). Probably the easiest
way to do this is to use indent(1) utility. Simply run Since kernel programming is always asynchronous,
indent --linux-style on your module’s source before there is no main() function that Linux executes
letting anyone to see it. sequentially to run your module. Instead, you provide
callbacks for various events, like this:

102 www.linuxvoice.com
KERNEL CODING

static int __init reverse_init(void)
{
Navigation
printk(KERN_INFO “reverse device has been registered\n”);
The Linux kernel is the ultimate source for everything
return 0;
you may need when developing modules. However,
} it’s quite big, and you may have trouble trying to
find what you are after. Luckily, there are tools that
static void __exit reverse_exit(void) make it easier to navigate large codebases. First of
{ all, there is Cscope – a venerable tool that runs in a
printk(KERN_INFO “reverse device has been unregistered\n”); terminal. Simply run make cscope && cscope in the
} kernel sources top-level directory. Cscope integrates
well with Vim and Emacs, so you can use it without
module_init(reverse_init); leaving the comfort of your favorite editor.
module_exit(reverse_exit);
If terminal-based tools aren’t your cup of tea,
visit http://lxr.free-electrons.com. It is a web-based
Here, we define functions to be called on the
kernel navigation tool with not quie as many features
module’s insertion and removal. Only the first one is
as Cscope (for example, you can’t easily find usages
required. For now, they simply print a message to the for the function), but it still provides enough for the
kernel ring buffer (accessible from the userspace via quick lookups.
the dmesg command); KERN_INFO is a log level (note
there is no comma). __init and __exit are attributes –
the pieces of metadata attached to functions (or if (!buffer_size)
variables). Attributes are rarely seen in userspace C return -1;
code but are pretty common in the kernel. Everything printk(KERN_INFO
marked with __init is recycled after the initialisation “reverse device has been registered, buffer size is %lu
(remember the old “Freeing unused kernel memory…” bytes\n”,
message?). __exit denotes functions that are safe to buffer_size);
optimise out when the code is built statically into the return 0;
kernel. Finally, the module_init() and module_exit() }
macros set reverse_init() and reverse_exit() functions
as lifecycle callbacks for our module. The actual Non-zero return value from a module init function indicates a
function names aren’t important; you can call them failure.
init() and exit() or start() and stop(), if you wish. They Now it’s time to compile the module. You will need
are declared static and hence invisible outside your the headers for the kernel version you are running
module. In fact, any function in the kernel is invisible (linux-headers or equivalent package) and build-
unless explicitly exported. However, prefixing your essential (or analogous). Next, it’s time to create a
functions with a module name is a common boilerplate Makefile:
convention among kernel programmers. obj-m += reverse.o
These are bare bones – let’s make things more all:
interesting. Modules can accept parameters, like this: make -C /lib/modules/$(shell uname -r)/build M=$(PWD)
# modprobe foo bar=1 modules
The modinfo command displays all parameters clean:
accepted by the module, and these are also available make -C /lib/modules/$(shell uname -r)/build M=$(PWD)
under /sys/module/<name>/parameters as files. Our clean
module will need a buffer to store phrases – let’s Now, call make to build your first module. If you
make its size user-configurable. Add the following typed everything correctly, you will find reverse.ko in
three lines just below MODULE_DESCRIPTION():
Reversing a word is simple,
static unsigned long buffer_size = 8192;
but it is also a main
module_param(buffer_size, ulong, (S_IRUSR | S_IRGRP | S_ building block for reversing
IROTH)); a phrase.
MODULE_PARM_DESC(buffer_size, “Internal buffer size”);
Here, we define a variable to store the value, wrap it
into a parameter, and make it readable by everyone via
sysfs. The parameter’s description (the last line)
appears in the modinfo’s output.
As the user can set buffer_size directly, we need to
sanitize it in reverse_init(). You should always check
the data that comes outside the kernel – if you don’t,
you are opening yourself to kernel panics or even
security holes.
static int __init reverse_init()
{

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CODING KERNEL

the current directory. Insert it with sudo insmod static struct file_operations reverse_fops = {
reverse.ko, and run: .owner = THIS_MODULE,
$ dmesg | tail -1 .open = reverse_open,
[ 5905.042081] reverse device has been registered, buffer size is ...
8192 bytes .llseek = noop_llseek
Congratulations! However, for now this line is telling };
lies – there is no device node yet. Let’s fix it. Again, reverse_fops contains a set of callbacks
(also known as methods) to be executed when
Miscellaneous devices userspace code opens a device, reads from it, writes
In Linux, there is a special character device type called to it or closes the file descriptor. If you omit any of
“miscellaneous” (or simply “misc”). It is designed for these, a sensible fallback will be used instead. That’s
small device drivers with a single entry point, and is why we explicitly set the llseek method to noop_
exactly what we need. All misc devices share the llseek(), which (as the name implies) does nothing.
same major number (10), so the one driver (drivers/ The default implementation changes a file pointer, and
char/misc.c) can look after all of them, and they are we don’t want our device to be seekable now (this will
distinguished by their minor numbers. In all other be your home assignment for today).
senses, they are just normal character devices.
To register a minor number (and an entry point) for I open at the close
the device, you declare struct misc_device, fill its Let’s implement the methods. We’ll allocate a new
fields (note the syntax), and call misc_register() with a buffer for each file descriptor opened, and free it on
pointer to this structure. For this to work, you will also close. This is not really safe: if a userspace application
need to include the linux/miscdevice.h header file: leaks descriptors (perhaps intentionally), it may hog
static struct miscdevice reverse_misc_device = { the RAM, and render the system unusable. You should
.minor = MISC_DYNAMIC_MINOR, always think about these possibilities in the real world,
.name = “reverse”, but for the tutorial, it’s acceptable.
.fops = &reverse_fops We’ll need a structure to describe the buffer. The
}; kernel provides many generic data structures: linked
static int __init reverse_init() lists (which are double-linked), hash tables, trees and
{ so on. However, buffers are usually implemented from
... scratch. We will call ours “struct buffer”:
misc_register(&reverse_misc_device); struct buffer {
printk(KERN_INFO ... char *data, *end, *read_ptr;
} unsigned long size;
Here, we request a first available (dynamic) minor };
number for the device named “reverse”; th ellipsis data is a pointer to the string this buffer stores, and
indicates omitted code that we’ve already seen. Don’t end is the first byte after the string end. read_ptr is
forget to unregister the device on the module’s where read() should start reading the data from. The
teardown: buffer size is stored for the completeness – for now,
static void __exit reverse_exit(void) we don’t use this field. You shouldn’t assume the
{ users of your structure will correctly initialise all of
misc_deregister(&reverse_misc_device); these, so it is better to encapsulate buffer allocation
... and deallocation in functions. They are usually named
} buffer_alloc() and buffer_free().
The ‘fops’ field stores a pointer to a struct file_ static struct buffer *buffer_alloc(unsigned long size)
operations (declared in linux/fs.h), and this is the {
entry point for our module. reverse_fops is defined as: struct buffer *buf;
buf = kzalloc(sizeof(*buf), GFP_KERNEL);
if (unlikely(!buf))
Avoid root if possible goto out;
...
By default, /dev/reverse is available to root only, so out:
you’ll have to run your test programs with sudo. To return buf;
fix this, create /lib/udev/rules.d/99-reverse.rules file
}
that contains:
Kernel memory is allocated with kmalloc() and
SUBSYSTEM==”misc”, KERNEL==”reverse”, MODE=”0666”
Don’t forget to reinsert the module. Making device freed with kfree(); the kzalloc() flavour sets the
nodes accessible to non-root users is generally not a memory to all-zeroes. Unlike standard malloc(), its
good idea, but it is quite useful during development. kernel counterpart receives flags specifying the type
This is not to mention that running test binaries as of memory requested in the second argument. Here,
root is not a good idea either. GFP_KERNEL means we need a normal kernel
memory (not in DMA or high-memory zones) and the

104 www.linuxvoice.com
KERNEL CODING

When not to write a kernel module
Kernel programming is fun, but writing You develop a filesystem – try FUSE
(and especially debugging) kernel code (fuse.sf.net).
in a real-world project requires certain You are extending Netfilter –
skills. In general, you should descend to libnetfilter_queue may help you
the kernel level only if there is no other then (www.netfilter.org/projects/
way to solve your problem. Chances are libnetfilter_queue).
you can stay in the userspace if: Generally, native kernel code will
You develop a USB driver – have a perform better, but for many projects
Our first module is small but real: it registers a device look at libusb (www.libusb.org). this performance loss isn’t crucial.
node and has its own entry in sysfs.

function can sleep (reschedule the process) if needed. method do if there is no data in the buffer yet? In
sizeof(*buf) is a common way to get the size of a userspace, the read() call would block until the data is
structure accessible via pointer. available. In the kernel, you must wait. Luckily, there is
You should always check kmalloc()’s return value: a mechanism for this, and it is called ‘wait queues’.
dereferencing NULL pointer will result in kernel panic. The idea is simple. If a current process needs to
Also note the use of unlikely() macro. It (and the wait for some event, its descriptor (a struct task_
opposite likely() macro) is widely used in the kernel to struct stored as ‘current’) is put into non-runnable
signify that the condition is almost always true (or (sleeping) state and added to a queue. Then
false). It doesn’t affect control flow, but helps modern schedule() is called to select another process to run. A
processors to boost performance with branch code that generates the event uses the queue to wake
prediction. up the waiters by putting them back to the TASK_
Finally, note the gotos. They are often considered RUNNING state. The scheduler will select one of them
evil, however, the Linux kernel (and some other system somewhere in the future. Linux has several non-
software) employs them to implement centralised runnable process states, most notably TASK_
function exiting. This results in less deeply nested and INTERRUPTIBLE (a sleep that can be interrupted with
more readable code, and is much like the try-ctach a signal) and TASK_KILLABLE (a sleeping process
blocks used in higher-level languages. that can be killed). All of this should be handled
With buffer_alloc() and buffer_free() in place, the correctly, and wait queues do this for you.
implementation of the open and close methods A natural place to store our read wait queue head is
becomes pretty straightforward. struct buffer, so start with adding wait_queue_head_t
static int reverse_open(struct inode *inode, struct file *file) read_queue field to it. You should also include linux/
{ sched.h. A wait queue can be declared statically with
int err = 0; DECLARE_WAITQUEUE() macro. In our case, dynamic
file->private_data = buffer_alloc(buffer_size); initialisation is needed, so add this line to buffer_
... alloc():
return err; init_waitqueue_head(&buf->read_queue);
} We wait for the data to be available; or for read_ptr !=
struct file is a standard kernel data structure that end condition to become true. We also want the wait
stores information about an opened file, like current to be interruptible (say, by Ctrl+C). So the “read”
file position (file->f_pos), flags (file->f_flags), or open method should start like this:
mode (file->f_mode). Another field, file->private_data static ssize_t reverse_read(struct file *file, char __user * out,
is used to associate the file with some arbitrary data. size_t size, loff_t * off)
Its type is void *, and it is opaque to the kernel outside {
the file’s owner. We store a buffer there. struct buffer *buf = file->private_data;
If the buffer allocation fails, we indicate this to the ssize_t result;
calling user space code by returning negative value while (buf->read_ptr == buf->end) {
(-ENOMEM). A C library doing open(2) system call if (file->f_flags & O_NONBLOCK) {
(probably, glibc) will detect this and set errno result = -EAGAIN;
appropriately. goto out;
}
Learn to read and write if (wait_event_interruptible
“Read” and “write” methods are where the real job is (buf->read_queue, buf->read_ptr != buf->end)) {
done. When data is written to a buffer, we drop its result = -ERESTARTSYS;
previous contents and reverse the phrase in-place, goto out;
without any temporary storage. The read method }
simply copies the data from the kernel buffer into the }
userspace. But what should the reverse_read() ...

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CODING KERNEL

reverse_phrase() does all heavy lifting. It relies on the
reverse_word() function, which is quite short and
marked inline. This is another common optimisation;
however, you shouldn’t overuse it, since aggressive
inlining makes the kernel image unnecessarily large.
Finally, we need to wake up processes waiting for
the data at read_queue, as described earlier. wake_
up_interruptible() does just that:
wake_up_interruptible(&buf->read_queue);
Phew! You now have a kernel module that at least
compiles. It’s time to test it.

Surprise, surprise!
Compile the module and load it into the kernel:
$ make
$ sudo insmod reverse.ko buffer_size=2048
$ lsmod
reverse 2419 0
Ever wondered how
We loop until the data is available and use wait_ $ ls -l /dev/reverse
the read(2) system call
reaches reverse_read()? event_interruptible() (it’s a macro, not a function, crw-rw-rw- 1 root root 10, 58 Feb 22 15:53 /dev/reverse
This diagram explains. that’s why the queue is passed by value) to wait if it Everything seems to be in place. Now, to test how
isn’t. If wait_event_interruptible() is, well, interrupted, it the module works, we’ll write a small program that
returns a non-zero value, which we translate to reverses its first command line argument. The main()
-ERESTARTSYS. This code means the system call function (sans error checking) may look like this:
should be restarted. file->f_flags check accounts for int fd = open(“/dev/reverse”, O_RDWR);
files opened in non-blocking mode: if there is no data, write(fd, argv[1], strlen(argv[1]));
we return -EAGAIN. read(fd, argv[1], strlen(argv[1]));
We can’t use if() instead of while(), since there can printf(“Read: %s\n”, argv[1]);
be many processes waiting for the data. When the Run it as:
write method awakes them, the scheduler chooses $ ./test ‘A quick brown fox jumped over the lazy dog’
the one to run in an unpredictable way, so by the time Read: dog lazy the over jumped fox brown quick A
this code is given a chance to execute, the buffer can It works! Play with it a little: try passing single-word or
be empty again. Now we need to copy the data from single-letter phrases, empty or non-English strings (if
buf->data to the userspace. The copy_to_user() you have a keyboard layout set) and anything else.
kernel function does just that: Now let’s make things a little trickier. We’ll create
size = min(size, (size_t) (buf->end - buf->read_ptr)); two processes that share the file descriptor (and
if (copy_to_user(out, buf->read_ptr, size)) { hence the kernel buffer). One will continuously write
result = -EFAULT; strings to the device, and another will read them. The
goto out; fork(2) system call is used in the example below, but
} pthreads will work as well. I also omitted the code that
The call can fail if the user space pointer is wrong; if opens and closes the device and does the error
this happen, we return -EFAULT. Remember not to checking (again):
trust anything coming outside the kernel! char *phrase = “A quick brown fox jumped over the lazy dog”,
buf->read_ptr += size; if (fork())
result = size; /* Parent is the writer */
out: while (1)
return result; write(fd, phrase, len);
} else
Simple arithmetic is needed so the data can be read /* child is the reader */
in arbitrary chunks. The method returns the number while (1) {
of bytes read or an error code. read(fd, buf, len);
Write method is simpler and shorter. First, we check printf(“Read: %s\n”, buf);
that the buffer have enough space, then we use the }
copy_from_userspace() function to get the data. Then What you expect this program to output? Below is
read_ptr and end pointers are reset and the buffer what I’ve got on my laptop:
contents are reversed: Read: dog lazy the over jumped fox brown quick A
buf->end = buf->data + size; Read: A kcicq brown fox jumped over the lazy dog
buf->read_ptr = buf->data; Read: A kciuq nworb xor jumped fox brown quick A
if (buf->end > buf->data) Read: A kciuq nworb xor jumped fox brown quick A
reverse_phrase(buf->data, buf->end - 1); ...

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What’s going on here? It’s a race. We thought read
and write were atomic, or executed one instruction at Debugging kernel code
a time from the beginning till the end. However the
Perhaps the most common debugging in the Makefile. After that, use dmesg to
kernel is a concurrent beast, and it can easily method in the kernel is printing. You view debug messages generated by
reschedule the process running the kernel-mode part can use plain printk() (presumably with pr_debug() or pr_devel().
of the write operation somewhere inside reverse_ KERN_DEBUG log level) if you wish. Alternatively, you can send debug
phrase() function. If the process that does read() is However, there are better ways. Use messages directly to the console. To do
scheduled before the writer is given a chance to finish, pr_debug() or dev_dbg(), if you are this, either set console_loglevel kernel
it will see the data in an inconsistent state. Such bugs writing a device driver that has its own variable to 8 or greater (echo 8 > /proc/
are really hard to debug. But how to fix it? “struct device”: they support the sys/kernel/printk) or temporarily print
Basically, we need to ensure that no read method dynamic debug (dyndbg) feature and the debug message in question at the
can be executed until the write method returns. If you can be enabled or disabled on request high log level like KERN_ERR. Naturally,
(see Documentation/dynamic-debug- you should remove debug statements of
ever programmed a multi-threaded application, you’ve
howto.txt). For pure development this kind before publishing your code.
probably seen synchronisation primitives (locks) like
messages, use pr_devel(), which Note that kernel messages appear on
mutexes or semaphores. Linux has them as well, but becomes a no-op unless DEBUG is the console, not in a terminal emulator
there are nuances. Kernel code can run in the process defined. To enable DEBUG for our window such as Xterm; that’s why you’ll
context (working “on behalf” of the userspace code, as module, include: find recommendations not to do kernel
our methods do) and in the interrupt context (for CFLAGS_reverse.o := -DDEBUG development in the X environment.
example, in an IRQ handler). If you are in the process
context and a lock you need has already been taken,
you simply sleep and retry until you succeed. You goto out;
can’t sleep in the interrupt context, so the code spins }
in a loop until the lock become available. The }
corresponding primitive is called a spinlock, but in our Below is our “wait for the data” loop. You should
case, a simple mutex – an object that only one never sleep when holding a mutex, or a situation
process can “hold” at the given time – is sufficient. A called a “deadlock” may occur. So, if there is no data,
real-world code may also use a read-write semaphore, we release the mutex and call wait_event_
for performance reasons. interruptible(). When it returns, we reacquire the
Locks always protect some data (in our case, a mutex and continue as usual:
“struct buffer” instance), and it is very common to if (copy_to_user(out, buf->read_ptr, size)) {
embed them in a structure they are protecting. So we result = -EFAULT;
add a mutex (‘struct mutex lock’) into the “struct goto out_unlock;
buffer”. We must also initialise the mutex with mutex_ }
init(); buffer_alloc() is a good place for this. The code ...
that uses mutexes must also include linux/mutex.h. out_unlock:
A mutex is much like a traffic light – it’s useless mutex_unlock(&buf->lock);
unless drivers look at it and follow the signals. So we out:
need to update reverse_read() and reverse_read() to return result;
acquire the mutex before doing anything to the buffer Finally, the mutex is unlocked when the function
and release it when they are done. Let’s have a look at ends or if an error occurs while the mutex is being
read method – write works just the same way: held. Recompile the module (don’t forget to reload it)
static ssize_t reverse_read(struct file *file, char __user * out, and run the second test again. You should see no
size_t size, loff_t * off) corrupted data now.
{
struct buffer *buf = file->private_data; What’s next?
ssize_t result; Now you have a taste of kernel hacking. We’ve just
if (mutex_lock_interruptible(&buf->lock)) { scratched the surface of the topic, and there is much
result = -ERESTARTSYS; more to see. Our first module was intentionally simple,
goto out; however the concepts you learned will stay the same
} in more complex scenarios as well. Concurrency,
We acquire the lock at the very beginning of the method tables, registering callbacks, putting
function. mutex_lock_interruptible() either grabs the processes to sleep and waking them up are things
mutex and returns or puts the process to sleep until that every kernel hacker should be comfortable with, OVER TO YOU
the mutex is available. As before, _interruptible suffix and now you’ve seen all of them in action. Maybe your Do you want to see some
means the sleep can be interrupted with a signal. kernel code will end up in the mainline Linux source more kernel magic –
while (buf->read_ptr == buf->end) { tree some day – drop us a line if this happens! perhaps intercepting file
access or creating your
mutex_unlock(&buf->lock); own iptables module?
/* ... wait_event_interruptible() here ... */ Dr Valentine Sinitsyn edited the Russian edition of O’Reilly’s Tell us what you think at
if (mutex_lock_interruptible(&buf->lock)) { Understanding the Linux Kernel, has a PhD in physics, and is forums.linuxvoice.com or
currently doing clever things with Python. letters@linuxvoice.com
result = -ERESTARTSYS;

www.linuxvoice.com 107
MASTERCLASS FILEZILLA

MASTERCLASS
Essential Linux tools explained – this month, say hello
BEN EVERARD to the Filezilla FTP client and learn the power of SSH.

GET TO KNOW FILEZILLA
Does you email have a draconian attachment size limit?
Never mind – learn Filezilla and get your files moving.

M
oving files between machines is something
JOHN LANE that most of us need to do at some point.
Whether that’s simply as a backup,
updating a web server or another task, it helps to have
a flexible tool that can handle multiple file transfer
protocols. Today, we’ll take a look at FileZilla, a
cross-platform GUI application released under the
GPL version 2. It’s implemented using wxWidgets, a
cross-platform GUI library that uses GTK on Linux, so
it doesn’t have many dependencies. You should find it
in your distribution’s package repository:
sudo apt-get install filezilla FileZilla’s window has six main areas, but basically your
The first time that you start FileZilla you should take local files are on the left, with romote files on the right.
a minute to familiarise yourself with the layout, but the
main thing to grasp is that you transfer files between listings. The transfer queue lists the files that have, or
a local directory, displayed on the left, and a remote will be, transferred, and the toolbar contains buttons
one, which is displayed on the right. that you can use to show and hide the individual areas
The main window comprises the toolbar and quick of the main window.
connect bar, a message log, and local and remote file You can connect to a remote site immediately by
filling in the boxes in the Quickconnect Bar, which lies
across the top of the window. The default protocol is
SFTP authentication FTP, but you can also use SFTP or FTPS by prefixing
Many SSH servers require that you have convert its format. It will save a copy of the host name with the protocol.
a key for authentication. If you are your key in a new PPK-formatted file of sftp://mysite.example.org
connecting to such a server, Filezilla your choosing. You should enter the username and password for the
gives you two choices. The first, and One important point to note is that site. See the boxout if you are using SFTP and need to
probably best, is to add the required key FileZilla does not work with keys that authenticate with a private key instead of a password
to your ssh-agent and ensure that the require a passphrase. If you try to add
(leave the password field empty in this case).
SSH_AUTH_SOCK environment variable such a key, you will be prompted to
is set before launching Filezilla. convert it. This will require you to enter
To start an SSH agent and add your your passphrase and will save a copy of Secure FTP
key use this command: your key with its passphrase removed. FileZilla also checks and warns about unmatched
eval `ssh-agent` && ssh-add SFTP server host keys in a similar way to SSH (it
The second way is to add your keys internally uses PuTTY code and, if you use that too,
into FileZilla. To do this, go to Settings > then they share the same cache file (which can be
SFTP to add them. FileZilla natively found at ~.putty/sshhostkeys).
works with keys saved in PPK format, Once you are connected to a remote server, its files
which is the PuTTY Private Key format If you feel uncomfortable about and directories are displayed in the remote site part of
(PuTTY is an SSH client that works on the security implications of using the window. The local site window similarly displays
Windows as well as Linux). unprotected private keys, you may files and directories on your local machine. Navigating
If, as is most likely, you are using an prefer not to load them into Filezilla
around both of these areas is done in the same way,
OpenSSH key, FileZilla will prompt to and, instead, use the SSH Agent.
and to copy a file you drag and drop between them.
When you do so, the transfer queue updates to reflect

108 www.linuxvoice.com
FILEZILLA MASTERCLASS

which gets closed, or can be opened as a new tab. A
Settings tabbed interface is added to the main screen when
you have two or more sites open, and each tab
FileZilla has a lot of options that you can tweak to contains local remote and transfer windows for one
your taste. The settings dialog, accessed via the Edit PRO TIP
connection.
menu, enables you to control many aspects of the Instead of connecting to a site, you can perform a
For documentation and
application, including how connections are made and support resources, go to
manual transfer of a single file. This function, http://filezilla-project.org
how the various protocols work. You can also control
accessed through Transfer > Manual Transfer is a
how FileZilla performs file transfers and customise
the user interface. way to move one file to or from a remote site,
although connecting and using drag and drop is a
more intuitive way to achieve the same result.

Memorable paths
If you find yourself regularly navigating to many local
and remote paths, you’ll want to check out the
Bookmarks function. A bookmark defines either local
or a remote path and can be global or site-specific.
When a bookmark is selected, the Local and Remote
windows change to those paths.
When you’ve tweaked it exactly how you want it, your A useful feature that can be enabled on a bookmark
config settings are saved to ~/.filezilla/filezilla.xml. or on a site as a whole (through the Site Manager) is
synchronised browsing. This selects a local and
remote directory path and
the transfers that take place. This is separated into
three tabs: Queued Files shows transfers yet to take
keeps both in sync as you
navigate either the local or
“Firefox was one of the first
place; Failed Transfers and Successful Transfers are remote file views. You’ll be browsers to offer the tabbed
self-explanatory.
The Local and Remote windows each have a pop-up
warned if you try to
navigate to a path on one
browsing model.”
context menu (right-click) that you can use to create that doesn’t exist on the
and delete files and directories, set permissions and other; continuing to that location disables
so-on. The options vary depending whether the menu synchronised browsing.
pops up in the context of a file, directory or neither. It’s just as important to realise what synchronised
browsing isn’t: it is not an automated mechanism to
Quick connections synchronise the contents of local and remote
FileZilla remembers connections that you make with filesystems. Filezilla doesn’t do that. If you want
the Quickconnect bar, as we have done here, and they automated synchronisation there are other more
can be repeated by selecting them from the drop- appropriate tools available, not least rsync. But, for a
down beside the Quickconnect button. The nice clean GUI-based general-purpose file transfer Use the Site Manager to
Quickconnect bar allows you to build up a history of utility, FileZilla has it covered. organise the sites that you
connect to.
connections that you can re-use quickly and easily,
but there is another way to manage connections if
you want more control – the Site Manager.
The Site Manager allows you to organise the sites
that you connect to and offers more options to control
how those connections operate. It is, however, distinct
from the Quickconnect bar, and sites added to one do
not appear in the other. You can add a currently
connected site to the Site Manager by using File >
Copy Current Connection To Site Manager. This opens
the Site Manager ready to accept the new site and
defaults its fields with the details for the current
connection. Press OK to complete adding the site.
There are two ways that you can connect to a site
that is saved in the Site Manager. The first way is to
open the Site Manager, select the site and click
Connect. The other, more direct route, is to right-click
the Site Manager toolbar icon and select the site from
the drop-down menu that is displayed.
As you use FileZilla to connect to more sites, each
new connection can either replace an existing one,

www.linuxvoice.com 109
MASTERCLASS SSH

AN INTRODUCTION TO SSH
Get to grips with SSH and lord it over remote machines…

I
f you use more than one computer then you will is what you asked for, you can enter yes to continue
probably, at some point, want to do something on the connection.
one that isn’t in front of you. The authenticity of host ‘remotehost (192.168.1.15)’ can’t be
SSH (the Secure Shell) isn’t another command-line established.
shell like Bash – it’s a networking protocol that you can ECDSA key fingerprint is 6d:c4:cf:43:75:a5:79:e0:74:a0:b7:22:b
use to connect securely to a remote computer across 7:da:e1:25.
an insecure network like the internet. It establishes an Are you sure you want to continue connecting (yes/no)?
encrypted connection to a remote computer, executes This happens because SSH uses public-key
a command there and redirects its input and output cryptography to authenticate any server you connect
across the connection. In SSH, the shell is like a to. The server responds with its public key as
wrapper surrounding a path through an insecure confirmation of its identity but your SSH client doesn’t
network that encrypts everything sent through it. recognise it. Your client tries to compare keys it
The way most people use SSH is as a command- receives with copies kept in a file at ~/.ssh/known_
line to enter commands on a remote machine, which hosts. When you connect for the first time, it has no
you can then work on as if it were there in front of you. copy to compare against, so it displays the warning
This remote login is what SSH does if it isn’t given a message instead. When you respond yes to continue
specific command. connecting, you tell your client to trust the server and
Using SSH requires a client on the local computer it adds the received key to the known_hosts file.
and a server on the remote one. The implementation On subsequent connections, the client compares
found on most Linux distributions is called OpenSSH, the key sent by the server with the one previously
and both the client and server packages should be in recorded and aborts the connection if they don’t
your distro’s repository; they may even be installed by match. It provides some useful information to help
default. On Debian-based systems, the client you investigate and resolve the problem. The
(openssh-client) is installed by default, but you may connection is authenticated if the client and server
need to install the server on machines that you want keys match.
to connect to:
sudo apt-get install openssh-server The keymaster
This installs and starts the SSH server. Once you have SSH requires that each server has a unique key that
set up a remote host you can connect like this: consists of the public key it sends to connecting
ssh remotehost clients and a corresponding private key that it keeps
where remotehost is the hostname of the remote secret. Most distributions automatically generate
computer (or you can use its IP address). You will be these server host keys when SSH is installed or
prompted for your password on that remote machine. started for the first time.
SSH assumes your local and remote user names are What has happened so far is that the client and
the same unless you tell it to use a different one server have established a secure communications
ssh user@remotehost channel but you have yet to authenticate yourself as a
SSH gives a dark and You will see a serious-looking warning when you user. The simplest way to do this is by entering a
foreboding warning when connect to a remote host for the first time, but password but you can (and, arguably, should) use a
host keys don’t match. assuming you’re happy that what you’ve connected to key exchange instead. Before you can do this you
need to generate your own key:
ssh-keygen -t rsa
which, by default, saves keys in ~/.ssh with the private
key in a file called id_rsa and the public key in id_rsa.
pub. You can choose whether to enter a passphrase
to protect your private key. If you do, you will need to
enter the passphrase whenever you use the private
key. An unprotected private key is only as secure as
the file it’s in.
You need to copy your public key (not your private
key) to any remote server that you want to connect to,
and there is an easy way to do this:
ssh-copy-id remotehost
You will need to authenticate before the key can be
copied, which will require that you enter your

110 www.linuxvoice.com
SSH MASTERCLASS

password for the remote machine. If the remote SSH
server has disabled password authentication then this Server configuration
will not work and you will need to ask the remote
The SSH server has a configuration file, usually
server’s administrator to copy your public key onto the
located at /etc/ssh/sshd_config. Some settings you
server for you. Your public key is stored on the remote should review are listed below.
server in ~/.ssh/authorized_keys.
Set PasswordAuthentication to No to disable
password authentication. Users will need to supply
Beyond the command-line their public key before they can connect.
Many people use SSH just to get a command prompt
Set PermitRootLogin to No to prevent remote
on a remote server, but you can do more than that. If
logins as the root user.
you enable X forwarding on the server then you can
Set X11Forwarding to Yes to allow use of X
launch GUI applications and have them display on
applications over SSH.
your local desktop. The -X parameter enables this
mode. If you wanted, for example, to run a Firefox Use AllowUsers or DenyUsers if you need to
restrict the users who can connect.
browser on the remote host, you could do:
ssh -X remotehost firefox Use Banner to display a message when a
Forwarding the X protocol over SSH is an example connection is established. Specify a file, usually
/etc/issue containing the message text.
of ‘tunnelling’, and you can use SSH as a tunnel for any
network traffic. The example below forwards email After changing the server configuration, reload it
with
SMTP traffic to a mail server on the remote network:
sudo killall -HUP sshd
ssh -N -f remotehost -L 25:remotemailhost:25
If you ever need to re-generate a server’s keys:
The parameters run SSH as a daemon (-f) without rm /etc/ssh/ssh_host_* && ssh-keygen -A
executing a remote command (-N) because we’re
tunnelling instead. The -L 25:remotehost:25 tells SSH
to listen on a local port 25 and forward any traffic it If you need constant access to many remote files,
receives across the SSH connection to remotehost you may prefer to mount a remote filesystem and use
and onwards to remotemailhost port 25. it as if it were a local one. You can use sshfs to do this
Another use for SSH is to copy files, and there are a – it’s a userspace filesystem built on top of Fuse.
few ways to do this. The scp (secure copy) command sudo apt-get install sshfs
enables you to copy files between your local sudo adduser myuser fuse
filesystem and a remote SSH server. You use it This installs it and adds your user ID to the fuse
similarly to the regular cp command, except that the group, enabling you to mount a directory on a remote
remote path is prefixed with the remote host name SSH server:
(and, optionally, username): mkdir ~.mountpoint
scp /local/path user@remotehost:/remote/path sshfs remotehost:/remote/path ~/mountpoint
You can also copy files with sftp, which looks and You can then interact with the remote files as if they
PRO TIP
feels like a basic FTP client. It’s also handled by the were local. When you are ready to unmount the file With the ‘ssh agent’ you
only need to enter your
SSH server, so nothing additional is required to use it. system, use this command: passphrase the first time
sftp remotehost fusermount -u ~/mountpoint it’s needed.

Securing SSH
SSH is a secure protocol, but there are steps that you
can take to increase its security. The first thing most
admins will do is insist that users supply their public
key and disable password authentication.
You may also restrict what connecting users can
do. This is another use for the ~/.ssh/authorized_
keys file. By prefixing a user’s key with a command,
any connection will run that command regardless of
what the user requested.
command=”/usr/bin/something args...” ssh-rsa AAAAB3Nza-
C1yc...
You might expose an SSH server on the internet so
that you can connect to a server in a distant location. If
you do this, you can change the SSH port from its
default of 22 to a more obscure port of your choice.

John Lane is a technology consultant with a penchant for
Gnome has the Gnome Virtual Filesystem (GVFS), which Linux. He helps new business start-ups make the most of
open source.
natively supports SSH mounts.

www.linuxvoice.com 111
DVDPAGES

Distros, videos, applications, games, podcasts and more…
DVD 002
SHOWCASING THE BEST OF FOSS
Welcome to the second Linux Voice a whopping nine desktop And then there are videos, apps
DVD. It’s been fantastic to hear environments and window and other gems to explore – open
your feeback about the ﬁrst issue, managers. It’s a great way to index.html for the full lowdown.
so thank you to everyone who got explore the different interfaces in We hope you enjoy the disc, and if
in touch. This issue’s DVD, like last the Linux and open source world. you have a digital subscription to
month’s, is an 8GB dual-layer beast Then we have gNewSense, a Linux Voice, you can get the DVD
jam-packed with software, videos, completely pure distribution (ie ISO image from our website at
podcasts and much more. without a single byte of non-free www.linuxvoice.com.
We have the latest release software) that even the notoriously
of Mageia, a superb desktop picky Richard Stallman doesn’t Mike Saunders, Disc Editor
distribution that boasts have a beef with. mike@linuxvoice.com

Complete desktop distro

Mageia 4
A ﬁrst-class Mandriva spin-off with over 4,400 packages.

O
ne of the biggest reasons for distro you’re a long-time Linux user or are new to
hopping is trying out a new desktop the operating system, it’s well worth a try.
environment. Sure, most big-name The minimum system requirements are:
distros have a range of desktops, but they’re 32 or 64-bit x86 CPU
often not integrated very well, so you have to 512MB RAM
choose a speciﬁc distro to get a good 6GB hard drive space
version of, say, KDE or Gnome. Still, we recommend having 1GB+ RAM
Mageia is different: the version on our for smooth running. To install Mageia, just
DVD includes nine desktops and window boot your PC from the Linux Voice DVD – ie
managers, all polished and integrated start your PC with the disc in the drive. (On
excellently. So you can try the latest versions some older PCs, you may need to change
of KDE, Gnome, Cinnamon, MATE, Xfce, the boot order in your BIOS so that the DVD After installation, click the pencil and paper
Enlightenment and more from a single drive boots ﬁrst, so consult your PC icon in the login screen to choose your desktop
distro. We’ve included the complete 3.7GB documentation or your local Google.) or window manager.
edition of Megeia 4 on the disc, and whether Choose ‘Install Mageia 4’ from the boot
menu and follow the prompts. If you’re
completely new to Linux, before installing it’s
worth loading up index.html from the disc in
Firefox, scrolling down to the Videos section,
and watching our videos about installing
and using Mageia – they’ll get you prepared
before you do the installation yourself.
If you want the complete nine-desktop
experience, at the Desktop Selection phase
of the installation, choose the Custom
option. You can then pick and choose which
desktops and WMs you want installed. And
Choose Custom during the Desktop Selection step for more information on Mageia, visit its
of the installation for a big range of options. website at www.mageia.org.

112 www.linuxvoice.com
DVDPAGES

RMS-friendly distro

gNewSense 3.1
Only free (as in speech) software – a very pure distro.

W
e’re not big fans of the name, but various small changes and ﬁxes. We’ve
we really like gNewSense. It’s a included this release (the 64-bit version) on
GNU/Linux distro that only the Linux Voice DVD: to install it, just boot
contains completely free software: that is, your PC from the disc and choose one of the
no binary-only drivers or patent-iffy media gNewSense options from the boot menu. As
codecs that many other desktop distros well as booting the distro in live mode If you hated earlier versions of Gnome 3, it’s
include. Richard Stallman, creator of GNU (which runs from the DVD and has an worth giving the desktop another chance.
and the awesome GPL licence, thinks that installer icon on the desktop) you can also
most GNU/Linux distributions don’t help to perform a text-mode installation, which is and all the usual tools are present. There’s
advance the cause of software freedom by ideal if you want to install on older machines nothing especially fancy about it – it’s just a
installing those extras – so he likes or servers. solid all-round distro with a ﬁrm focus on
gNewSense for its purity. gNewSense is based on Debian, so any freedom. If you love the spirit and goals of
Now, gNewSense isn’t as up-to-date as skills you’ve learnt during your time with free software, give it a go. And if you need
many other desktop distros doing the Debian and/or Ubuntu will come in useful any help or support, pop over to the project’s
rounds, but the new 3.1 release does include here. It uses apt for package management website: www.gnewsense.org.

Not just software!

Linux Voice videos
Mageia, FOSSpicks, Retrode and newbie guides.

W
hen we started work on the ﬁrst and Vorbis format, so they will play straight
Linux Voice DVD, we wanted to away in Firefox without the need for any
make it much more than just a extra apps or media codecs.
compendium of the latest Linux software. Firstly there are the aforementioned
We wanted it to be a part of the magazine, videos explaining how to install Mageia and
website and community as a whole, so we explore its KDE desktop. Then we have a Thanks to the completely free and open
decided to make some videos showcasing look at some apps covered in FOSSpicks, Theora+Vorbis video codec, you can watch our
things covered in the mag. And we’ve including the rather cool Android-x86. Next videos straight away in Firefox.
continued that for this month’s DVD. there’s a quick look at the Retrode as
Open index.html in Firefox and scroll covered on page 22. Finally, Graham made use it, based on Linux Mint 16 from last
down to the Videos section. Click the links to some great “new to Linux” videos explaining issue’s DVD. They’re essential viewing if
watch the videos – they’re in Ogg Theora what Linux is, how to install it and how to you’re taking your ﬁrst steps in Linux.

And there’s more!
Podcasts, software, games, Linux From Scratch...
Legends tell of a faraway group of people, Also on the disc are a bunch of new desktop
isolated from the rest of the world, with barely applications including LibreOfﬁce 4.2 (in Deb
any contact with mankind. Little is known and RPM formats), PCManFM 1.2 and Anjuta
about these beings, but one thing is for sure: 3.11.4. We have a selection of hot games
they’re missing out on the most important such as Ember 0.7.1, along with the latest
development in human history. They’ve never kernel and GCC code for those who want
heard the Linux Voice Podcast. to live on the bleeding edge. Oh, and if you
Maybe this issue’s DVD will reach their have a few hours spare and want to get your
settlements at some point, so we’ve included hands dirty with a new project, try Linux From
the latest episodes for their listening Scratch: it teaches you how to make your own
enjoyment. There’s lots of Linux banter, lots custom Linux distribution, compiling every Join the online RPG WorldForge using Ember,
of discoveries, and lots of off-topicness. little piece yourself. It’s ace. and buy pigs from strangers.

www.linuxvoice.com 113
/DEV/RANDOM/

Final thoughts, musings and reflections
Nick Veitch
was the original editor
of Linux Format, a
role he played until he Inspirational photo
got bored and went of Jono Bacon.
to work at Canonical
instead. Splitter!

M
oney is great. You can do all sorts
Lots of phones (not Desktop PC for
of things with it. It really is rather all Ubuntu). Linux gaming and
amazing, and we should all pay photo/video editing.
due homage to Pheidon, who struck the ﬁrst
recognised coins (in Argos, or possibly Lydia) in
about 700BC, since which time it has certainly
been a much easier trip to the supermarket. Panasonic bluetooth
headphones connected via a
It is therefore a good thing that Linux Voice Electronics hobby box on cable because Bluetooth on
is giving away 50% of its proﬁts to the needy of floor, contains various Linux sucks :)
open source. Loads of projects, big and small, Arduino/RPi stuff.
useful and silly, will no doubt beneﬁt. But, in a
terrible paraphrasing of Bob Geldof, “it’s not
enough”. Not that I think 50% isn’t enough – I
mean money isn’t enough.
My Linux setup Alan Pope
Many a time, when I have been confronted by
a pernicious bug, or some rogue documentation
@uupc podcaster and Canonical chap shows us the ofﬁce.
or an unintelligible user interface, I have taken a
crisp £20 out of my wallet and waved it at the What version of Linux are you was doing, but the terminal seemed cool!
screen saying “here, for the love of everything using at the moment? Next stop Debian, then Ubuntu where I’ve
that doesn’t suck, ﬁx this”. Sometimes I have got Ubuntu Trusty (which will become stayed for nine years.
up to £100, but the screen stares impassively 14.04) on laptop and desktop. Also,
back, taunting my impotence. Ubuntu on the Nexus 4’s and Nexus 7’s. What Free Software/open source
As I have already mentioned, money is One 2012 Nexus 7 running Android can’t you live without?
incredibly useful. Projects can use it for much- constantly running irssi-notiﬁer to alert Linux itself. While I use the entire
needed hardware, or maybe for inescapable ISP me of IRC pings. stack every day, without the work
costs, attending events or securing an adequate done by the Linux kernel developers, I can’t
supply of caffeine… What desktop do you use? If we imagine most of the rest of it would be as
But. What projects often need, sometimes had to guess, we’ say… advanced and usable as it is.
even more than Bitcoins, is vitality, effort and … Unity on the laptop, desktop and
responsiveness. This is usually achieved by phone. What do other people love but
having a vibrant, involved community. There you can’t get on with?
have been dozens of articles online and What was the ﬁrst Linux setup KDE. I promised to try it for a full 6
elsewhere on different ways you can help open you ever used? months. Got intensely
source software, even if you can’t write code. Red Hat, which I got with a book in frustrated with it after a month and gave
Paying your way in open source is a good around 1996. I had no clue what I up, never looked back.
thing, but getting involved is better. If you like
software, support it. Get involved. Sometimes
little more is required to keep a software project
ticking along than just people turning up. Follow us on Twitter @linuxvoice!
114 www.linuxvoice.com
THANK YOU!

THANK YOU!
Linux Voice would like to say a huge thanks to everyone who
made this magazine possible. If you bought the Founder perk
during our IndieGogo campaign, and we missed you off the
Founders’ page in issue 1, we’re sorry. Many, many thanks.

Anthony Beavis, Auroraskyes, Patrick Allen, Peter Selley,
David Banks, Den Weatherall, Sally Henderson, Samuel Voss,
Kevan Vautier, Luis Joaquim, Sebastian Dixon-Lewis, Stephan
Marius Orintas, Mike Eaket, Diestelhorst, Tarquin Adams