# Miscellaneous Help

## borg help patterns

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 experimental `--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/*).

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 (‘’ 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, it must completely match from start to end, or must match from the start 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.
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.
Regular expressions, selector re:
  Regular expressions similar to those found in Perl are supported. Unlike shell patterns regular expressions are not required to match the complete path and any substring match is sufficient. It is strongly recommended to anchor patterns to the start (‘^’), to the end (‘$’) or both. Path separators (‘’ 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.
Path prefix, selector pp:
  This pattern style is useful to match whole sub-directories. The pattern pp:/data/bar matches /data/bar and everything therein.
Path full-match, selector pf:

  This pattern style is useful to match whole paths. This is kind of a pseudo pattern as it can not have any variable or unspecified parts - the full, precise path must be given. pf:/data/foo.txt matches /data/foo.txt 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.

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
    EOF
    $ borg create --exclude-from exclude.txt backup /

A more general and easier to use way to define filename matching patterns exists with the experimental `--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 -, both followed by a pattern. 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.

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.

An example `--patterns-from` 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
    # don't backup the other home directories
    - /home/*

## borg help placeholders

Repository (or Archive) URLs, `--prefix` and `--remote-path` values support these placeholders:

{hostname}
  The (short) hostname of the machine.
{fqdn}
  The full name of the machine.
{now}
  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}
{utcnow}
  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}
{user}
  The user name (or UID, if no name is available) of the user running borg.
{pid}
  The current process ID.
{borgversion}
  The version of borg, e.g.: 1.0.8rc1
{borgmajor}
  The version of borg, only the major version, e.g.: 1
{borgminor}
  The version of borg, only major and minor version, e.g.: 1.0
{borgpatch}
  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}`).

## 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:

none
  Do not compress.
lz4
  Use lz4 compression. High speed, low compression. (default)
zlib[,L]
  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.
lzma[,L]
  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.
auto,C[,L]
  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 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 ...