Miscellaneous Help

borg help patterns

When specifying one or more file paths in a Borg command that supports patterns for the respective option or argument, you can apply the patterns described here to include only desired files and/or exclude unwanted ones. Patterns can be used

  • for --exclude option,

  • in the file given with --exclude-from option,

  • for --pattern option,

  • in the file given with --patterns-from option and

  • for PATH arguments that explicitly support them.

Borg always stores all file paths normalized and relative to the current recursion root. The recursion root is also named PATH in Borg commands like borg create that do a file discovery, so do not confuse the root with the PATH argument of e.g. borg extract.

Starting with Borg 1.2, paths that are matched against patterns always appear relative. If you give /absolute/ as root, the paths going into the matcher will start with absolute/. If you give ../../relative as root, the paths will be normalized as relative/.

Borg supports different pattern styles. To define a non-default style for a specific pattern, prefix it with two characters followed by a colon ‘:’ (i.e. fm:path/*, sh:path/**).

Fnmatch, selector fm:

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. A leading path separator is always removed.

Shell-style patterns, selector sh:

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, {} containing comma-separated alternative patterns. A leading path separator is always removed.

Regular expressions, selector re:

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.

Path prefix, selector pp:

This pattern style is useful to match whole sub-directories. The pattern pp:root/somedir matches root/somedir and everything therein. A leading path separator is always removed.

Path full-match, selector pf:

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. A leading path separator is always removed.

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.


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 hash 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 ....


# Exclude '/home/user/file.o' but not '/home/user/file.odt':
$ borg create -e '*.o' archive /

# Exclude '/home/user/junk' and '/home/user/subdir/junk' but
# not '/home/user/importantjunk' or '/etc/junk':
$ borg create -e 'home/*/junk' archive /

# Exclude the contents of '/home/user/cache' but not the directory itself:
$ borg create -e home/user/cache/ archive /

# The file '/home/user/cache/important' is *not* backed up:
$ borg create -e home/user/cache/ archive / /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/' archive /

# Load exclusions from file
$ cat >exclude.txt <<EOF
# Comment line
# Example with spaces, no need to escape as it is processed by borg
some file with spaces.txt
$ borg create --exclude-from exclude.txt archive /

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, default pattern styles and patterns for inclusion and exclusion.

Root path prefix R

A recursion root path starts with the prefix R, followed by a path (a plain path, not a file pattern). Use this prefix to have the root paths in the patterns file rather than as command line arguments.

Pattern style prefix P

To change the default pattern style, use the P prefix, followed by the pattern style abbreviation (fm, pf, pp, re, sh). All patterns following this line will use this style until another style is specified.

Exclude pattern prefix -

Use the prefix -, followed by a pattern, to define an exclusion. This has the same effect as the --exclude option.

Exclude no-recurse pattern prefix !

Use the prefix !, followed by a pattern, to define an exclusion that does not recurse into subdirectories. This saves time, but prevents include patterns to match any files in subdirectories.

Include pattern prefix +

Use the prefix +, followed by a pattern, to define inclusions. This is useful to include paths that are covered in an exclude pattern and would otherwise not be backed up.

The first matching pattern is used, so if an include pattern matches before an exclude pattern, the file is backed up. Note that a no-recurse exclude stops examination of subdirectories so that potential includes will not match - use normal excludes for such use cases.


# Define the recursion root
R /
# Exclude all iso files in any directory
- **/*.iso
# Explicitly include all inside etc and root
+ etc/**
+ root/**
# Exclude a specific directory under each user's home directories
- home/*/.cache
# Explicitly include everything in /home
+ home/**
# Explicitly exclude some directories without recursing into them
! re:^(dev|proc|run|sys|tmp)
# Exclude all other files and directories
# that are not specifically included earlier.
- **

Tip: You can easily test your patterns with --dry-run and --list:

$ borg create --dry-run --list --patterns-from patterns.txt archive

This will list the considered files one per line, prefixed with a character that indicates the action (e.g. ‘x’ for excluding, see Item flags in borg create usage docs).


It’s possible that a sub-directory/file is matched while parent directories are not. In that case, parent directories are not backed up and thus their user, group, permission, etc. cannot be restored.

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.


# back up 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 archive pics

# back up only JPG/JPEG files (case insensitive) in all home directories:
borg create --pattern '+ re:\.jpe?g(?i)$' archive /home

# back up homes, but exclude big downloads (like .ISO files) or hidden files:
borg create --exclude 're:\.iso(?i)$' --exclude 'sh:home/**/.*' archive /home

# use a file with patterns (recursion root '/' via command line):
borg create --patterns-from patterns.lst archive /

The patterns.lst file could look like that:

# "sh:" pattern style is the default
# exclude caches
- home/*/.cache
# include susans home
+ home/susan
# also back up this exact file
+ pf:home/bobby/specialfile.txt
# don't back up the other home directories
- home/*
# don't even look in /dev, /proc, /run, /sys, /tmp (note: would exclude files like /device, too)
! re:^(dev|proc|run|sys|tmp)

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 archive /home/bobby /home/susan
borg create --patterns-from patternfile.lst archive


# 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.

borg help match-archives

The --match-archives option matches a given pattern against the list of all archive names in the repository.

It uses pattern styles similar to the ones described by borg help patterns:

Identical match pattern, selector id: (default)

Simple string match, must fully match exactly as given.

Shell-style patterns, selector sh:

Match like on the shell, wildcards like * and ? work.

Regular expressions, selector re:

Full regular expression support. This is very powerful, but can also get rather complicated.


# id: style
borg delete --match-archives 'id:archive-with-crap'
borg delete -a 'id:archive-with-crap'  # same, using short option
borg delete -a 'archive-with-crap'  # same, because 'id:' is the default

# sh: style
borg delete -a 'sh:home-kenny-*'

# re: style
borg delete -a 're:pc[123]-home-(user1|user2)-2022-09-.*'

borg help placeholders

Repository URLs, --name, -a / --match-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}}


borg create /path/to/repo::{hostname}-{user}-{utcnow} ...
borg create /path/to/repo::{hostname}-{now:%Y-%m-%d_%H:%M:%S%z} ...
borg prune -a 'sh:{hostname}-*' ...


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}).

borg help compression

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 explicitly give the compression level L (ranging from 1 to 22), it will use level 3.


Use zlib (“gz”) compression. Medium speed, medium compression. If you do not explicitly 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 explicitly 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.


Use compressed-size obfuscation to make fingerprinting attacks based on the observable stored chunk size more difficult. Note:

  • You must combine this with encryption, or it won’t make any sense.

  • Your repo size will be bigger, of course.

  • A chunk is limited by the constant MAX_DATA_SIZE (cur. ~20MiB).

The SPEC value determines how the size obfuscation works:

Relative random reciprocal size variation (multiplicative)

Size will increase by a factor, relative to the compressed data size. Smaller factors are used often, larger factors rarely.

Available factors:

1:     0.01 ..        100
2:     0.1  ..      1,000
3:     1    ..     10,000
4:    10    ..    100,000
5:   100    ..  1,000,000
6: 1,000    .. 10,000,000

Example probabilities for SPEC 1:

90   %  0.01 ..   0.1
 9   %  0.1  ..   1
 0.9 %  1    ..  10
 0.09% 10    .. 100

Randomly sized padding up to the given size (additive)

110: 1kiB (2 ^ (SPEC - 100))
120: 1MiB
123: 8MiB (max.)


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 ...
borg create --compression obfuscate,110,none ...
borg create --compression obfuscate,3,auto,zstd,10 ...
borg create --compression obfuscate,2,zstd,6 ...