The path/filenames used as input for the pattern matching start from the currently active recursion root. You usually give the recursion root(s) when invoking borg and these can be either relative or absolute paths.
So, when you give relative/ as root, the paths going into the matcher will look like relative/…/file.ext. When you give /absolute/ as root, they will look like /absolute/…/file.ext. This is meant when we talk about “full path” below.
File paths in Borg archives are always stored normalized and relative.
This means that e.g. borg create /path/to/repo ../some/path
will
store all files as some/path/…/file.ext and borg create
/path/to/repo /home/user
will store all files as
home/user/…/file.ext. Therefore, always use relative paths in your
patterns when matching archive content in commands like extract
or
mount
. Starting with Borg 1.2 this behaviour will be changed to
accept both absolute and relative paths.
A directory exclusion pattern can end either with or without a slash (‘/’). If it ends with a slash, such as some/path/, the directory will be included but not its content. If it does not end with a slash, such as some/path, both the directory and content will be excluded.
File patterns support these styles: fnmatch, shell, regular expressions,
path prefixes and path full-matches. By default, fnmatch is used for
--exclude
patterns and shell-style is used for the --pattern
option.
If followed by a colon (‘:’) the first two characters of a pattern are used as a style selector. Explicit style selection is necessary when a non-default style is desired or when the desired pattern starts with two alphanumeric characters followed by a colon (i.e. aa:something/*).
This is the default style for --exclude
and --exclude-from
.
These patterns use a variant of shell pattern syntax, with ‘*’ matching
any number of characters, ‘?’ matching any single character, ‘[…]’
matching any single character specified, including ranges, and ‘[!…]’
matching any character not specified. For the purpose of these patterns,
the path separator (backslash for Windows and ‘/’ on other systems) is not
treated specially. Wrap meta-characters in brackets for a literal
match (i.e. [?] to match the literal character ?). For a path
to match a pattern, the full path must match, or it must match
from the start of the full path to just before a path separator. Except
for the root path, paths will never end in the path separator when
matching is attempted. Thus, if a given pattern ends in a path
separator, a ‘*’ is appended before matching is attempted.
This is the default style for --pattern
and --patterns-from
.
Like fnmatch patterns these are similar to shell patterns. The difference
is that the pattern may include **/ for matching zero or more directory
levels, * for matching zero or more arbitrary characters with the
exception of any path separator.
Regular expressions similar to those found in Perl are supported. Unlike shell patterns regular expressions are not required to match the full path and any substring match is sufficient. It is strongly recommended to anchor patterns to the start (‘^’), to the end (‘$’) or both. Path separators (backslash for Windows and ‘/’ on other systems) in paths are always normalized to a forward slash (‘/’) before applying a pattern. The regular expression syntax is described in the Python documentation for the re module.
This pattern style is useful to match whole sub-directories. The pattern pp:root/somedir matches root/somedir and everything therein.
This pattern style is (only) useful to match full paths. This is kind of a pseudo pattern as it can not have any variable or unspecified parts - the full path must be given. pf:root/file.ext matches root/file.ext only.
Implementation note: this is implemented via very time-efficient O(1) hashtable lookups (this means you can have huge amounts of such patterns without impacting performance much). Due to that, this kind of pattern does not respect any context or order. If you use such a pattern to include a file, it will always be included (if the directory recursion encounters it). Other include/exclude patterns that would normally match will be ignored. Same logic applies for exclude.
Note
re:, sh: and fm: patterns are all implemented on top of the Python SRE engine. It is very easy to formulate patterns for each of these types which requires an inordinate amount of time to match paths. If untrusted users are able to supply patterns, ensure they cannot supply re: patterns. Further, ensure that sh: and fm: patterns only contain a handful of wildcards at most.
Exclusions can be passed via the command line option --exclude
. When used
from within a shell, the patterns should be quoted to protect them from
expansion.
The --exclude-from
option permits loading exclusion patterns from a text
file with one pattern per line. Lines empty or starting with the number sign
(‘#’) after removing whitespace on both ends are ignored. The optional style
selector prefix is also supported for patterns loaded from a file. Due to
whitespace removal, paths with whitespace at the beginning or end can only be
excluded using regular expressions.
To test your exclusion patterns without performing an actual backup you can
run borg create --list --dry-run ...
.
Examples:
# Exclude '/home/user/file.o' but not '/home/user/file.odt':
$ borg create -e '*.o' backup /
# Exclude '/home/user/junk' and '/home/user/subdir/junk' but
# not '/home/user/importantjunk' or '/etc/junk':
$ borg create -e '/home/*/junk' backup /
# Exclude the contents of '/home/user/cache' but not the directory itself:
$ borg create -e /home/user/cache/ backup /
# The file '/home/user/cache/important' is *not* backed up:
$ borg create -e /home/user/cache/ backup / /home/user/cache/important
# The contents of directories in '/home' are not backed up when their name
# ends in '.tmp'
$ borg create --exclude 're:^/home/[^/]+\.tmp/' backup /
# Load exclusions from file
$ cat >exclude.txt <<EOF
# Comment line
/home/*/junk
*.tmp
fm:aa:something/*
re:^/home/[^/]+\.tmp/
sh:/home/*/.thumbnails
# Example with spaces, no need to escape as it is processed by borg
some file with spaces.txt
EOF
$ borg create --exclude-from exclude.txt backup /
A more general and easier to use way to define filename matching patterns exists
with the --pattern
and --patterns-from
options. Using these, you may
specify the backup roots (starting points) and patterns for inclusion/exclusion.
A root path starts with the prefix R, followed by a path (a plain path, not a
file pattern). An include rule starts with the prefix +, an exclude rule starts
with the prefix -, an exclude-norecurse rule starts with !, all followed by a pattern.
Note
Via --pattern
or --patterns-from
you can define BOTH inclusion and exclusion
of files using pattern prefixes +
and -
. With --exclude
and
--exclude-from
ONLY excludes are defined.
Inclusion patterns are useful to include paths that are contained in an excluded path. The first matching pattern is used so if an include pattern matches before an exclude pattern, the file is backed up. If an exclude-norecurse pattern matches a directory, it won’t recurse into it and won’t discover any potential matches for include rules below that directory.
Note
It’s possible that a sub-directory/file is matched while parent directories are not. In that case, parent directories are not backed up thus their user, group, permission, etc. can not be restored.
Note that the default pattern style for --pattern
and --patterns-from
is
shell style (sh:), so those patterns behave similar to rsync include/exclude
patterns. The pattern style can be set via the P prefix.
Patterns (--pattern
) and excludes (--exclude
) from the command line are
considered first (in the order of appearance). Then patterns from --patterns-from
are added. Exclusion patterns from --exclude-from
files are appended last.
Examples:
# backup pics, but not the ones from 2018, except the good ones:
# note: using = is essential to avoid cmdline argument parsing issues.
borg create --pattern=+pics/2018/good --pattern=-pics/2018 repo::arch pics
# use a file with patterns:
borg create --patterns-from patterns.lst repo::arch
The patterns.lst file could look like that:
# "sh:" pattern style is the default, so the following line is not needed:
P sh
R /
# can be rebuild
- /home/*/.cache
# they're downloads for a reason
- /home/*/Downloads
# susan is a nice person
# include susans home
+ /home/susan
# also back up this exact file
+ pf:/home/bobby/specialfile.txt
# don't backup the other home directories
- /home/*
# don't even look in /proc
! /proc
You can specify recursion roots either on the command line or in a patternfile:
# these two commands do the same thing
borg create --exclude /home/bobby/junk repo::arch /home/bobby /home/susan
borg create --patterns-from patternfile.lst repo::arch
The patternfile:
# note that excludes use fm: by default and patternfiles use sh: by default.
# therefore, we need to specify fm: to have the same exact behavior.
P fm
R /home/bobby
R /home/susan
- /home/bobby/junk
This allows you to share the same patterns between multiple repositories without needing to specify them on the command line.
Repository (or Archive) URLs, --prefix
, --glob-archives
, --comment
and --remote-path
values support these placeholders:
The (short) hostname of the machine.
The full name of the machine.
The full name of the machine in reverse domain name notation.
The current local date and time, by default in ISO-8601 format. You can also supply your own format string, e.g. {now:%Y-%m-%d_%H:%M:%S}
The current UTC date and time, by default in ISO-8601 format. You can also supply your own format string, e.g. {utcnow:%Y-%m-%d_%H:%M:%S}
The user name (or UID, if no name is available) of the user running borg.
The current process ID.
The version of borg, e.g.: 1.0.8rc1
The version of borg, only the major version, e.g.: 1
The version of borg, only major and minor version, e.g.: 1.0
The version of borg, only major, minor and patch version, e.g.: 1.0.8
If literal curly braces need to be used, double them for escaping:
borg create /path/to/repo::{{literal_text}}
Examples:
borg create /path/to/repo::{hostname}-{user}-{utcnow} ...
borg create /path/to/repo::{hostname}-{now:%Y-%m-%d_%H:%M:%S} ...
borg prune --prefix '{hostname}-' ...
Note
systemd uses a difficult, non-standard syntax for command lines in unit files (refer to the systemd.unit(5) manual page).
When invoking borg from unit files, pay particular attention to escaping,
especially when using the now/utcnow placeholders, since systemd performs its own
%-based variable replacement even in quoted text. To avoid interference from systemd,
double all percent signs ({hostname}-{now:%Y-%m-%d_%H:%M:%S}
becomes {hostname}-{now:%%Y-%%m-%%d_%%H:%%M:%%S}
).
It is no problem to mix different compression methods in one repo, deduplication is done on the source data chunks (not on the compressed or encrypted data).
If some specific chunk was once compressed and stored into the repo, creating another backup that also uses this chunk will not change the stored chunk. So if you use different compression specs for the backups, whichever stores a chunk first determines its compression. See also borg recreate.
Compression is lz4 by default. If you want something else, you have to specify what you want.
Valid compression specifiers are:
Do not compress.
Use lz4 compression. Very high speed, very low compression. (default)
Use zstd (“zstandard”) compression, a modern wide-range algorithm. If you do not explicitely give the compression level L (ranging from 1 to 22), it will use level 3. Archives compressed with zstd are not compatible with borg < 1.1.4.
Use zlib (“gz”) compression. Medium speed, medium compression. If you do not explicitely give the compression level L (ranging from 0 to 9), it will use level 6. Giving level 0 (means “no compression”, but still has zlib protocol overhead) is usually pointless, you better use “none” compression.
Use lzma (“xz”) compression. Low speed, high compression. If you do not explicitely give the compression level L (ranging from 0 to 9), it will use level 6. Giving levels above 6 is pointless and counterproductive because it does not compress better due to the buffer size used by borg - but it wastes lots of CPU cycles and RAM.
Use a built-in heuristic to decide per chunk whether to compress or not. The heuristic tries with lz4 whether the data is compressible. For incompressible data, it will not use compression (uses “none”). For compressible data, it uses the given C[,L] compression - with C[,L] being any valid compression specifier.
Examples:
borg create --compression lz4 REPO::ARCHIVE data
borg create --compression zstd REPO::ARCHIVE data
borg create --compression zstd,10 REPO::ARCHIVE data
borg create --compression zlib REPO::ARCHIVE data
borg create --compression zlib,1 REPO::ARCHIVE data
borg create --compression auto,lzma,6 REPO::ARCHIVE data
borg create --compression auto,lzma ...