rdiff-backup - local/remote mirror and incremental backup
rdiff-backup [options]
[[[user@]host1.foo]::source_directory]
[[[user@]host2.foo]::destination_directory]
rdiff-backup {{ -l | --list-increments } |
--remove-older-than time_interval | --list-at-time
time | --list-changed-since time |
--list-increment-sizes | --verify | --verify-at-time
time}
[[[user@]host2.foo]::destination_directory]
rdiff-backup --calculate-average statfile1 statfile2
...
rdiff-backup --test-server
[user1]@host1.net1::path
[[user2]@host2.net2::path]
...
rdiff-backup is a script, written in python(1) that
backs up one directory to another. The target directory ends up a copy
(mirror) of the source directory, but extra reverse diffs are stored in a
special subdirectory of that target directory, so you can still recover
files lost some time ago. The idea is to combine the best features of a
mirror and an incremental backup. rdiff-backup also preserves symlinks,
special files, hardlinks, permissions, uid/gid ownership, and modification
times.
rdiff-backup can also operate in a bandwidth efficient
manner over a pipe, like rsync(1). Thus you can use ssh and
rdiff-backup to securely back a hard drive up to a remote location, and only
the differences will be transmitted. Using the default settings,
rdiff-backup requires that the remote system accept ssh connections, and
that rdiff-backup is installed in the user's PATH on the remote
system. For information on other options, see the section on REMOTE
OPERATION.
Note that you should not write to the mirror directory
except with rdiff-backup. Many of the increments are stored as reverse
diffs, so if you delete or modify a file, you may lose the ability to
restore previous versions of that file.
Finally, this man page is intended more as a precise description
of the behavior and syntax of rdiff-backup. New users may want to check out
the examples.html file included in the rdiff-backup distribution.
- -b, --backup-mode
- Force backup mode even if first argument appears to be an increment or
mirror file.
- --calculate-average
- Enter calculate average mode. The arguments should be a number of
statistics files. rdiff-backup will print the average of the listed
statistics files and exit.
- --carbonfile
- Enable backup of MacOS X carbonfile information.
- --check-destination-dir
- If an rdiff-backup session fails, running rdiff-backup with this option on
the destination dir will undo the failed directory. This happens
automatically if you attempt to back up to a directory and the last backup
failed.
- --compare
- This is equivalent to '--compare-at-time now'
- --compare-at-time
time
- Compare a directory with the backup set at the given time. This can be
useful to see how archived data differs from current data, or to check
that a backup is current. This only compares metadata, in the same way
rdiff-backup decides whether a file has changed.
- --compare-full
- This is equivalent to '--compare-full-at-time
now'
- --compare-full-at-time
time
- Compare a directory with the backup set at the given time. To compare
regular files, the repository data will be copied in its entirety to the
source side and compared byte by byte. This is the slowest but most
complete compare option.
- --compare-hash
- This is equivalent to '--compare-hash-at-time
now'
- --compare-hash-at-time
time
- Compare a directory with the backup set at the given time. Regular files
will be compared by computing their SHA1 digest on the source side and
comparing it to the digest recorded in the metadata.
- --create-full-path
- Normally only the final directory of the destination path will be created
if it does not exist. With this option, all missing directories on the
destination path will be created. Use this option with care: if there is a
typo in the remote path, the remote filesystem could fill up very quickly
(by creating a duplicate backup tree). For this reason this option is
primarily aimed at scripts which automate backups.
- --current-time
seconds
- This option is useful mainly for testing. If set, rdiff-backup will use it
for the current time instead of consulting the clock. The argument is the
number of seconds since the epoch.
- --exclude
shell_pattern
- Exclude the file or files matched by shell_pattern. If a directory
is matched, then files under that directory will also be matched. See the
FILE SELECTION section for more information.
- --exclude-device-files
- Exclude all device files. This can be useful for security/permissions
reasons or if rdiff-backup is not handling device files correctly.
- --exclude-fifos
- Exclude all fifo files.
- --exclude-filelist
filename
- Excludes the files listed in filename. If filename is
handwritten you probably want --exclude-globbing-filelist instead.
See the FILE SELECTION section for more information.
- --exclude-filelist-stdin
- Like --exclude-filelist, but the list of files will be read from
standard input. See the FILE SELECTION section for more
information.
- --exclude-globbing-filelist
filename
- Like --exclude-filelist but each line of the filelist will be
interpreted according to the same rules as --include and
--exclude.
- --exclude-globbing-filelist-stdin
- Like --exclude-globbing-filelist, but the list of files will be
read from standard input.
- --exclude-other-filesystems
- Exclude files on file systems (identified by device number) other than the
file system the root of the source directory is on.
- --exclude-regexp
regexp
- Exclude files matching the given regexp. Unlike the --exclude
option, this option does not match files in a directory it matches. See
the FILE SELECTION section for more information.
- --exclude-special-files
- Exclude all device files, fifo files, socket files, and symbolic
links.
- --exclude-sockets
- Exclude all socket files.
- --exclude-symbolic-links
- Exclude all symbolic links. This option is automatically enabled if the
backup source is running on native Windows to avoid backing-up NTFS
reparse points.
- --exclude-if-present
filename
- Exclude directories if filename is present. This option needs to
come before any other include or exclude options.
- --force
- Authorize a more drastic modification of a directory than usual (for
instance, when overwriting of a destination path, or when removing
multiple sessions with --remove-older-than). rdiff-backup will
generally tell you if it needs this. WARNING: You can cause data
loss if you mis-use this option. Furthermore, do NOT use this option when
doing a restore, as it will DELETE FILES, unless you absolutely know what
you are doing.
- --group-mapping-file
filename
- Map group names and ids according the the group mapping file
filename. See the USERS AND GROUPS section for more
information.
- --include
shell_pattern
- Similar to --exclude but include matched files instead. Unlike
--exclude, this option will also match parent directories of
matched files (although not necessarily their contents). See the FILE
SELECTION section for more information.
- --include-filelist
filename
- Like --exclude-filelist, but include the listed files instead. If
filename is handwritten you probably want
--include-globbing-filelist instead. See the FILE SELECTION
section for more information.
- --include-filelist-stdin
- Like --include-filelist, but read the list of included files from
standard input.
- --include-globbing-filelist
filename
- Like --include-filelist but each line of the filelist will be
interpreted according to the same rules as --include and
--exclude.
- --include-globbing-filelist-stdin
- Like --include-globbing-filelist, but the list of files will be
read from standard input.
- --include-regexp
regexp
- Include files matching the regular expression regexp. Only files
explicitly matched by regexp will be included by this option. See
the FILE SELECTION section for more information.
- --include-special-files
- Include all device files, fifo files, socket files, and symbolic
links.
- --include-symbolic-links
- Include all symbolic links.
- --list-at-time
time
- List the files in the archive that were present at the given time. If a
directory in the archive is specified, list only the files under that
directory.
- --list-changed-since
time
- List the files that have changed in the destination directory since the
given time. See TIME FORMATS for the format of time. If a
directory in the archive is specified, list only the files under that
directory. This option does not read the source directory; it is used to
compare the contents of two different rdiff-backup sessions.
- -l,
--list-increments
- List the number and date of partial incremental backups contained in the
specified destination directory. No backup or restore will take place if
this option is given.
- --list-increment-sizes
- List the total size of all the increment and mirror files by time. This
may be helpful in deciding how many increments to keep, and when to
--remove-older-than. Specifying a subdirectory is allowable; then only the
sizes of the mirror and increments pertaining to that subdirectory will be
listed.
- --max-file-size
size
- Exclude files that are larger than the given size in bytes
- --min-file-size
size
- Exclude files that are smaller than the given size in bytes
- --never-drop-acls
- Exit with error instead of dropping acls or acl entries. Normally this may
happen (with a warning) because the destination does not support them or
because the relevant user/group names do not exist on the destination
side.
- --no-acls
- No Access Control Lists - disable backup of ACLs
- --no-carbonfile
- Disable backup of MacOS X carbonfile information
- --no-compare-inode
- This option prevents rdiff-backup from flagging a hardlinked file as
changed when its device number and/or inode changes. This option is useful
in situations where the source filesystem lacks persistent device and/or
inode numbering. For example, network filesystems may have mount-to-mount
differences in their device number (but possibly stable inode numbers);
USB/1394 devices may come up at different device numbers each remount (but
would generally have same inode number); and there are filesystems which
don't even have the same inode numbers from use to use. Without the option
rdiff-backup may generate unnecessary numbers of tiny diff files.
- --no-compression
- Disable the default gzip compression of most of the .snapshot and .diff
increment files stored in the rdiff-backup-data directory. A backup volume
can contain compressed and uncompressed increments, so using this option
inconsistently is fine.
- --no-compression-regexp
regexp
- Do not compress increments based on files whose filenames match regexp.
The default includes many common audiovisual and archive files, and may be
found in Globals.py.
- --no-eas
- No Extended Attributes support - disable backup of EAs.
- --no-file-statistics
- This will disable writing to the file_statistics file in the
rdiff-backup-data directory. rdiff-backup will run slightly quicker and
take up a bit less space.
- --no-hard-links
- Don't replicate hard links on destination side. If many hard-linked files
are present, this option can drastically decrease memory usage. This
option is enabled by default if the backup source or restore destination
is running on native Windows.
- --null-separator
- Use nulls (\0) instead of newlines (\n) as line separators, which may help
when dealing with filenames containing newlines. This affects the expected
format of the files specified by the --{include|exclude}-filelist[-stdin]
switches as well as the format of the directory statistics file.
- --parsable-output
- If set, rdiff-backup's output will be tailored for easy parsing by
computers, instead of convenience for humans. Currently this only applies
when listing increments using the -l or --list-increments
switches, where the time will be given in seconds since the epoch.
- --override-chars-to-quote
- If the filesystem to which we are backing up is not case-sensitive,
automatic 'quoting' of characters occurs. For example, a file
'Developer.doc' will be converted into ';068eveloper.doc'. To override
this behavior, you need to specify this option.
- --preserve-numerical-ids
- If set, rdiff-backup will preserve uids/gids instead of trying to preserve
unames and gnames. See the USERS AND GROUPS section for more
information.
- --print-statistics
- If set, summary statistics will be printed after a successful backup. If
not set, this information will still be available from the session
statistics file. See the STATISTICS section for more
information.
- -r, --restore-as-of
restore_time
- Restore the specified directory as it was as of restore_time. See
the TIME FORMATS section for more information on the format of
restore_time, and see the RESTORING section for more
information on restoring.
- --remote-cmd
cmd
- Deprecated. Please use --remote-schema instead
- --remote-schema
schema
- Specify an alternate method of connecting to a remote computer. This is
necessary to get rdiff-backup not to use ssh for remote backups, or if,
for instance, rdiff-backup is not in the PATH on the remote side. See the
REMOTE OPERATION section for more information.
- --remote-tempdir
path
- Adds the --tempdir option with argument path when invoking remote
instances of rdiff-backup.
- --remove-older-than
time_spec
- Remove the incremental backup information in the destination directory
that has been around longer than the given time. time_spec can be
either an absolute time, like "2002-01-04", or a time interval.
The time interval is an integer followed by the character s, m, h, D, W,
M, or Y, indicating seconds, minutes, hours, days, weeks, months, or years
respectively, or a number of these concatenated. For example, 32m means 32
minutes, and 3W2D10h7s means 3 weeks, 2 days, 10 hours, and 7 seconds. In
this context, a month means 30 days, a year is 365 days, and a day is
always 86400 seconds.
rdiff-backup cannot remove-older-than and back up or restore
in a single session. In order to both backup a directory and remove old
files in it, you must run rdiff-backup twice.
By default, rdiff-backup will only delete information from one
session at a time. To remove two or more sessions at the same time,
supply the --force option (rdiff-backup will tell you if
--force is required).
Note that snapshots of deleted files are covered by this
operation. Thus if you deleted a file two weeks ago, backed up
immediately afterwards, and then ran rdiff-backup with
--remove-older-than 10D today, no trace of that file would remain.
Finally, file selection options such as --include and --exclude don't
affect --remove-older-than.
- --restrict
path
- Require that all file access be inside the given path. This switch, and
the following two, are intended to be used with the --server switch to
provide a bit more protection when doing automated remote backups. They
are not intended as your only line of defense so please don't do
something silly like allow public access to an rdiff-backup server run
with --restrict-read-only.
- --restrict-read-only
path
- Like --restrict, but also reject all write requests.
- --restrict-update-only
path
- Like --restrict, but only allow writes as part of an incremental
backup. Requests for other types of writes (for instance, deleting
path) will be rejected.
- --server
- Enter server mode (not to be invoked directly, but instead used by another
rdiff-backup process on a remote computer).
- --ssh-no-compression
- When running ssh, do not use the -C option to enable compression.
--ssh-no-compression is ignored if you specify a new schema using
--remote-schema.
- --tempdir
path
- Sets the directory that rdiff-backup uses for temporary files to the given
path. The environment variables TMPDIR, TEMP, and TMP can also be used to
set the temporary files directory. See the documentation of the Python
tempfile module for more information.
- --terminal-verbosity
[0-9]
- Select which messages will be displayed to the terminal. If missing the
level defaults to the verbosity level.
- --test-server
- Test for the presence of a compatible rdiff-backup server as specified in
the following host::filename argument(s). The filename section will be
ignored.
- --user-mapping-file
filename
- Map user names and ids according to the user mapping file filename.
See the USERS AND GROUPS section for more information.
- -v[0-9],
--verbosity [0-9]
- Specify verbosity level (0 is totally silent, 3 is the default, and 9 is
noisiest). This determines how much is written to the log file.
- --verify
- This is short for --verify-at-time now
- --verify-at-time
now
- Check all the data in the repository at the given time by computing the
SHA1 hash of all the regular files and comparing them with the hashes
stored in the metadata file.
- -V, --version
- Print the current version and exit
There are two ways to tell rdiff-backup to restore a file or
directory. Firstly, you can run rdiff-backup on a mirror file and use the
-r or --restore-as-of options. Secondly, you can run it on an
increment file.
For example, suppose in the past you have run:
rdiff-backup /usr /usr.backup
to back up the /usr directory into the /usr.backup directory, and
now want a copy of the /usr/local directory the way it was 3 days ago placed
at /usr/local.old.
One way to do this is to run:
rdiff-backup -r 3D /usr.backup/local /usr/local.old
where above the "3D" means 3 days (for other ways to
specify the time, see the TIME FORMATS section). The
/usr.backup/local directory was selected, because that is the directory
containing the current version of /usr/local.
Note that the option to --restore-as-of always specifies an
exact time. (So "3D" refers to the instant 72 hours before the
present.) If there was no backup made at that time, rdiff-backup restores
the state recorded for the previous backup. For instance, in the above case,
if "3D" is used, and there are only backups from 2 days and 4 days
ago, /usr/local as it was 4 days ago will be restored.
The second way to restore files involves finding the corresponding
increment file. It would be in the /backup/rdiff-backup-data/increments/usr
directory, and its name would be something like
"local.2002-11-09T12:43:53-04:00.dir" where the time indicates it
is from 3 days ago. Note that the increment files all end in
".diff", ".snapshot", ".dir", or
".missing", where ".missing" just means that the file
didn't exist at that time (finally, some of these may be gzip-compressed,
and have an extra ".gz" to indicate this). Then running:
rdiff-backup
/backup/rdiff-backup-data/increments/usr/local.<time>.dir
/usr/local.old
would also restore the file as desired.
If you are not sure exactly which version of a file you need, it
is probably easiest to either restore from the increments files as described
immediately above, or to see which increments are available with
-l/--list-increments, and then specify exact times into
-r/--restore-as-of.
rdiff-backup uses time strings in two places. Firstly, all of the
increment files rdiff-backup creates will have the time in their filenames
in the w3 datetime format as described in a w3 note at
http://www.w3.org/TR/NOTE-datetime. Basically they look like
"2001-07-15T04:09:38-07:00", which means what it looks like. The
"-07:00" section means the time zone is 7 hours behind UTC.
Secondly, the -r, --restore-as-of, and
--remove-older-than options take a time string, which can be
given in any of several formats:
- 1.
- the string "now" (refers to the current time)
- 2.
- a sequences of digits, like "123456890" (indicating the time in
seconds after the epoch)
- 3.
- A string like "2002-01-25T07:00:00+02:00" in datetime
format
- 4.
- An interval, which is a number followed by one of the characters s, m, h,
D, W, M, or Y (indicating seconds, minutes, hours, days, weeks, months, or
years respectively), or a series of such pairs. In this case the string
refers to the time that preceded the current time by the length of the
interval. For instance, "1h78m" indicates the time that was one
hour and 78 minutes ago. The calendar here is unsophisticated: a month is
always 30 days, a year is always 365 days, and a day is always 86400
seconds.
- 5.
- A date format of the form YYYY/MM/DD, YYYY-MM-DD, MM/DD/YYYY, or
MM-DD-YYYY, which indicates midnight on the day in question, relative to
the current timezone settings. For instance, "2002/3/5",
"03-05-2002", and "2002-3-05" all mean March 5th,
2002.
- 6.
- A backup session specification which is a non-negative integer followed by
'B'. For instance, '0B' specifies the time of the current mirror, and '3B'
specifies the time of the 3rd newest increment.
In order to access remote files, rdiff-backup opens up a pipe to a
copy of rdiff-backup running on the remote machine. Thus rdiff-backup must
be installed on both ends. To open this pipe, rdiff-backup first splits the
filename into host_info::pathname. It then substitutes host_info into the
remote schema, and runs the resulting command, reading its input and
output.
The default remote schema is 'ssh -C %s rdiff-backup --server'
where host_info is substituted for '%s'. So if the host_info is
user@host.net, then rdiff-backup runs 'ssh user@host.net rdiff-backup
--server'. Using --remote-schema, rdiff-backup can invoke an arbitrary
command in order to open up a remote pipe. For instance,
rdiff-backup --remote-schema 'cd /usr; %s' foo
'rdiff-backup --server'::bar
is basically equivalent to (but slower than)
rdiff-backup foo /usr/bar
Concerning quoting, if for some reason you need to put two
consecutive colons in the host_info section of a host_info::pathname
argument, or in the pathname of a local file, you can quote one of them by
prepending a backslash. So in 'a\::b::c', host_info is 'a::b' and the
pathname is 'c'. Similarly, if you want to refer to a local file whose
filename contains two consecutive colons, like 'strange::file', you'll have
to quote one of the colons as in 'strange\::file'. Because the backslash is
a quote character in these circumstances, it too must be quoted to get a
literal backslash, so 'foo\::\\bar' evaluates to 'foo::\bar'. To make things
more complicated, because the backslash is also a common shell quoting
character, you may need to type in '\\\\' at the shell prompt to get a
literal backslash (if it makes you feel better, I had to type in 8
backslashes to get that in this man page...). And finally, to include a
literal % in the string specified by --remote-schema, quote it with another
%, as in %%.
Although ssh itself may be secure, using rdiff-backup in the
default way presents some security risks. For instance if the server is run
as root, then an attacker who compromised the client could then use
rdiff-backup to overwrite arbitrary server files by "backing up"
over them. Such a setup can be made more secure by using the sshd
configuration option command="rdiff-backup --server"
possibly along with the --restrict* options to rdiff-backup. For more
information, see the web page, the wiki, and the entries for the
--restrict* options on this man page.
rdiff-backup has a number of file selection options. When
rdiff-backup is run, it searches through the given source directory and
backs up all the files matching the specified options. This selection system
may appear complicated, but it is supposed to be flexible and easy-to-use.
If you just want to learn the basics, first look at the selection examples
in the examples.html file included in the package, or on the web at
http://rdiff-backup.nongnu.org/examples.html
rdiff-backup's selection system was originally inspired by
rsync(1), but there are many differences. (For instance, trailing
backslashes have no special significance.)
The file selection system comprises a number of file selection
conditions, which are set using one of the following command line options:
--exclude, --exclude-filelist, --exclude-device-files,
--exclude-fifos, --exclude-sockets,
--exclude-symbolic-links, --exclude-globbing-filelist,
--exclude-globbing-filelist-stdin, --exclude-filelist-stdin,
--exclude-regexp, --exclude-special-files, --include,
--include-filelist, --include-globbing-filelist,
--include-globbing-filelist-stdin, --include-filelist-stdin,
and --include-regexp. Each file selection condition either matches or
doesn't match a given file. A given file is excluded by the file selection
system exactly when the first matching file selection condition specifies
that the file be excluded; otherwise the file is included. When backing up,
if a file is excluded, rdiff-backup acts as if that file does not exist in
the source directory. When restoring, an excluded file is considered not to
exist in either the source or target directories.
For instance,
rdiff-backup --include /usr --exclude /usr /usr
/backup
is exactly the same as
rdiff-backup /usr /backup
because the include and exclude directives match exactly the same
files, and the --include comes first, giving it precedence.
Similarly,
rdiff-backup --include /usr/local/bin --exclude
/usr/local /usr /backup
would backup the /usr/local/bin directory (and its contents), but
not /usr/local/doc.
The include, exclude,
include-globbing-filelist, and exclude-globbing-filelist
options accept extended shell globbing patterns. These patterns can
contain the special patterns *, **, ?, and
[...]. As in a normal shell, * can be expanded to any string
of characters not containing "/", ? expands to any
character except "/", and [...] expands to a single
character of those characters specified (ranges are acceptable). The new
special pattern, **, expands to any string of characters whether or
not it contains "/". Furthermore, if the pattern starts with
"ignorecase:" (case insensitive), then this prefix will be removed
and any character in the string can be replaced with an upper- or lowercase
version of itself.
If you need to match filenames which contain the above globbing
characters, they may be escaped using a backslash "\". The
backslash will only escape the character following it so for ** you
will need to use "\*\*" to avoid escaping it to the *
globbing character.
Remember that you may need to quote these characters when typing
them into a shell, so the shell does not interpret the globbing patterns
before rdiff-backup sees them.
The --exclude pattern option matches a file iff:
- 1.
- pattern can be expanded into the file's filename, or
- 2.
- the file is inside a directory matched by the option.
Conversely, --include pattern matches a file iff:
- 1.
- pattern can be expanded into the file's filename,
- 2.
- the file is inside a directory matched by the option, or
- 3.
- the file is a directory which contains a file matched by the option.
For example,
--exclude /usr/local
matches /usr/local, /usr/local/lib, and /usr/local/lib/netscape.
It is the same as --exclude /usr/local --exclude '/usr/local/**'.
--include /usr/local
specifies that /usr, /usr/local, /usr/local/lib, and
/usr/local/lib/netscape (but not /usr/doc) all be backed up. Thus you don't
have to worry about including parent directories to make sure that included
subdirectories have somewhere to go. Finally,
--include
ignorecase:'/usr/[a-z0-9]foo/*/**.py'
would match a file like /usR/5fOO/hello/there/world.py. If it did
match anything, it would also match /usr. If there is no existing file that
the given pattern can be expanded into, the option will not match /usr.
The --include-filelist, --exclude-filelist,
--include-filelist-stdin, and --exclude-filelist-stdin options
also introduce file selection conditions. They direct rdiff-backup to read
in a file, each line of which is a file specification, and to include or
exclude the matching files. Lines are separated by newlines or nulls,
depending on whether the --null-separator switch was given. Each line in a
filelist is interpreted similarly to the way extended shell patterns
are, with a few exceptions:
- 1.
- Globbing patterns like *, **, ?, and [...] are
not expanded.
- 2.
- Include patterns do not match files in a directory that is included. So
/usr/local in an include file will not match /usr/local/doc.
- 3.
- Lines starting with "+ " are interpreted as include directives,
even if found in a filelist referenced by --exclude-filelist.
Similarly, lines starting with "- " exclude files even if they
are found within an include filelist.
For example, if the file "list.txt" contains the lines:
/usr/local
- /usr/local/doc
/usr/local/bin
+ /var
then "--include-filelist list.txt" would include /usr, /usr/local, and
/usr/local/bin. It would exclude /usr/local/doc, /usr/local/doc/python, etc.
It neither excludes nor includes /usr/local/man, leaving the fate of this
directory to the next specification condition. Finally, it is undefined what
happens with /var. A single file list should not contain conflicting file
specifications.
The --include-globbing-filelist and
--exclude-globbing-filelist options also specify filelists, but each
line in the filelist will be interpreted as a globbing pattern the way
--include and --exclude options are interpreted (although
"+ " and "- " prefixing is still allowed). For instance,
if the file "globbing-list.txt" contains the lines:
dir/foo
+ dir/bar
Then "--include-globbing-filelist globbing-list.txt" would be exactly
the same as specifying "--include dir/foo --include dir/bar --exclude
**" on the command line.
Finally, the --include-regexp and --exclude-regexp
allow files to be included and excluded if their filenames match a python
regular expression. Regular expression syntax is too complicated to explain
here, but is covered in Python's library reference. Unlike the
--include and --exclude options, the regular expression
options don't match files containing or contained in matched files. So for
instance
--include '[0-9]{7}(?!foo)'
matches any files whose full pathnames contain 7 consecutive
digits which aren't followed by 'foo'. However, it wouldn't match /home even
if /home/ben/1234567 existed.
There can be complications preserving ownership across systems.
For instance the username that owns a file on the source system may not
exist on the destination. Here is how rdiff-backup maps ownership on the
source to the destination (or vice-versa, in the case of restoring):
- 1.
- If the --preserve-numerical-ids option is given, the remote files will
always have the same uid and gid, both for ownership and ACL entries. This
may cause unames and gnames to change.
- 2.
- Otherwise, attempt to preserve the user and group names for ownership and
in ACLs. This may result in files having different uids and gids across
systems.
- 3.
- If a name cannot be preserved (e.g. because the username does not exist),
preserve the original id, but only in cases of user and group ownership.
For ACLs, omit any entry that has a bad user or group name.
- 4.
- The --user-mapping-file and --group-mapping-file options
override this behavior. If either of these options is given, the policy
described in 2 and 3 above will be followed, but with the mapped user and
group instead of the original. If you specify both
--preserve-numerical-ids and one of the mapping options, the
behavior is undefined.
The user and group mapping files both have the same form:
old_name_or_id1:new_name_or_id1
old_name_or_id2:new_name_or_id2
<etc>
Each line should contain a name or id, followed by a colon
":", followed by another name or id. If a name or id is not
listed, they are treated in the default way described above.
When restoring, the above behavior is also followed, but note that
the original source user/group information will be the input, not the
already mapped user/group information present in the backup repository. For
instance, suppose you have mapped all the files owned by alice in the
source so that they are owned by ben in the repository, and now you
want to restore, making sure the files owned originally by alice are
still owned by alice. In this case there is no need to use any of the
mapping options. However, if you wanted to restore the files so that the
files originally owned by alice on the source are now owned by
ben, you would have to use the mapping options, even though you just
want the unames of the repository's files preserved in the restored
files.
Every session rdiff-backup saves various statistics into two
files, the session statistics file at
rdiff-backup-data/session_statistics.<time>.data and the directory
statistics file at rdiff-backup-data/directory_statistics.<time>.data.
They are both text files and contain similar information: how many files
changed, how many were deleted, the total size of increment files created,
etc. However, the session statistics file is intended to be very readable
and only describes the session as a whole. The directory statistics file is
more compact (and slightly less readable) but describes every directory
backed up. It also may be compressed to save space.
Statistics-related options include --print-statistics and
--null-separator.
Also, rdiff-backup will save various messages to the log file,
which is rdiff-backup-data/backup.log for backup sessions and
rdiff-backup-data/restore.log for restore sessions. Generally what is
written to this file will coincide with the messages displayed to stdout or
stderr, although this can be changed with the --terminal-verbosity
option.
The log file is not compressed and can become quite large if
rdiff-backup is run with high verbosity.
If rdiff-backup finishes successfully, the exit status will be 0.
If there is an unrecoverable (critical) error, it will be non-zero (usually
1, but don't depend on this specific value). When setting up rdiff-backup to
run automatically (as from cron(8) or similar) it is probably a good
idea to check the exit code.
The gzip library in versions 2.2 and earlier of python (but fixed
in 2.3a1) has trouble producing files over 2GB in length. This bug will
prevent rdiff-backup from producing large compressed increments (snapshots
or diffs). A workaround is to disable compression for large uncompressable
files.
Ben Escoto <ben@emerose.org>
Feel free to ask me questions or send me bug reports, but you may
want to see the web page, mentioned below, first.
python(1), rdiff(1), rsync(1), ssh(1).
The main rdiff-backup web page is at http://rdiff-backup.nongnu.org/.
It has more information, links to the mailing list and CVS, etc.