path: root/docs/man/borg-patterns.1

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.TH BORG-PATTERNS 1 "2018-06-11" "" "borg backup tool"
.SH NAME
borg-patterns \- Details regarding patterns
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.SH DESCRIPTION
.sp
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.
.sp
So, when you give \fIrelative/\fP as root, the paths going into the matcher
will look like \fIrelative/.../file.ext\fP\&. When you give \fI/absolute/\fP as root,
they will look like \fI/absolute/.../file.ext\fP\&. This is meant when we talk
about "full path" below.
.sp
File patterns support these styles: fnmatch, shell, regular expressions,
path prefixes and path full\-matches. By default, fnmatch is used for
\fB\-\-exclude\fP patterns and shell\-style is used for the experimental \fB\-\-pattern\fP
option.
.sp
If followed by a colon (\(aq:\(aq) 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. \fIaa:something/*\fP).
.INDENT 0.0
.TP
.B \fI\%Fnmatch\fP, selector \fIfm:\fP
This is the default style for \fB\-\-exclude\fP and \fB\-\-exclude\-from\fP\&.
These patterns use a variant of shell pattern syntax, with \(aq*\(aq matching
any number of characters, \(aq?\(aq matching any single character, \(aq[...]\(aq
matching any single character specified, including ranges, and \(aq[!...]\(aq
matching any character not specified. For the purpose of these patterns,
the path separator (\(aq\(aq for Windows and \(aq/\(aq on other systems) is not
treated specially. Wrap meta\-characters in brackets for a literal
match (i.e. \fI[?]\fP to match the literal character \fI?\fP). 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 \(aq*\(aq is appended before matching is attempted.
.TP
.B Shell\-style patterns, selector \fIsh:\fP
This is the default style for \fB\-\-pattern\fP and \fB\-\-patterns\-from\fP\&.
Like fnmatch patterns these are similar to shell patterns. The difference
is that the pattern may include \fI**/\fP for matching zero or more directory
levels, \fI*\fP for matching zero or more arbitrary characters with the
exception of any path separator.
.TP
.B Regular expressions, selector \fIre:\fP
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 (\(aq^\(aq), to the end (\(aq$\(aq) or both. Path
separators (\(aq\(aq for Windows and \(aq/\(aq on other systems) in paths are
always normalized to a forward slash (\(aq/\(aq) before applying a pattern. The
regular expression syntax is described in the \fI\%Python documentation for
the re module\fP\&.
.TP
.B Path prefix, selector \fIpp:\fP
This pattern style is useful to match whole sub\-directories. The pattern
\fIpp:root/somedir\fP matches \fIroot/somedir\fP and everything therein.
.TP
.B Path full\-match, selector \fIpf:\fP
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.
\fIpf:root/file.ext\fP matches \fIroot/file.txt\fP only.
.sp
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.
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.sp
\fBNOTE:\fP
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.INDENT 3.5
\fIre:\fP, \fIsh:\fP and \fIfm:\fP 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 \fIre:\fP patterns.
Further, ensure that \fIsh:\fP and \fIfm:\fP patterns only contain a handful of
wildcards at most.
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.sp
Exclusions can be passed via the command line option \fB\-\-exclude\fP\&. When used
from within a shell the patterns should be quoted to protect them from
expansion.
.sp
The \fB\-\-exclude\-from\fP option permits loading exclusion patterns from a text
file with one pattern per line. Lines empty or starting with the number sign
(\(aq#\(aq) 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.
.sp
Examples:
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.sp
.nf
.ft C
# Exclude \(aq/home/user/file.o\(aq but not \(aq/home/user/file.odt\(aq:
$ borg create \-e \(aq*.o\(aq backup /

# Exclude \(aq/home/user/junk\(aq and \(aq/home/user/subdir/junk\(aq but
# not \(aq/home/user/importantjunk\(aq or \(aq/etc/junk\(aq:
$ borg create \-e \(aq/home/*/junk\(aq backup /

# Exclude the contents of \(aq/home/user/cache\(aq but not the directory itself:
$ borg create \-e /home/user/cache/ backup /

# The file \(aq/home/user/cache/important\(aq is *not* backed up:
$ borg create \-e /home/user/cache/ backup / /home/user/cache/important

# The contents of directories in \(aq/home\(aq are not backed up when their name
# ends in \(aq.tmp\(aq
$ borg create \-\-exclude \(aqre:^/home/[^/]+\e.tmp/\(aq backup /

# Load exclusions from file
$ cat >exclude.txt <<EOF
# Comment line
/home/*/junk
*.tmp
fm:aa:something/*
re:^/home/[^/]\e.tmp/
sh:/home/*/.thumbnails
EOF
$ borg create \-\-exclude\-from exclude.txt backup /
.ft P
.fi
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A more general and easier to use way to define filename matching patterns exists
with the experimental \fB\-\-pattern\fP and \fB\-\-patterns\-from\fP options. Using these, you
may specify the backup roots (starting points) and patterns for inclusion/exclusion.
A root path starts with the prefix \fIR\fP, 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.
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\(aqt recurse into it and won\(aqt discover any potential matches for
include rules below that directory.
.sp
Note that the default pattern style for \fB\-\-pattern\fP and \fB\-\-patterns\-from\fP is
shell style (\fIsh:\fP), so those patterns behave similar to rsync include/exclude
patterns. The pattern style can be set via the \fIP\fP prefix.
.sp
Patterns (\fB\-\-pattern\fP) and excludes (\fB\-\-exclude\fP) from the command line are
considered first (in the order of appearance). Then patterns from \fB\-\-patterns\-from\fP
are added. Exclusion patterns from \fB\-\-exclude\-from\fP files are appended last.
.sp
Examples:
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.INDENT 3.5
.sp
.nf
.ft C
# 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
.ft P
.fi
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.sp
The patterns.lst file could look like that:
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.sp
.nf
.ft C
# "sh:" pattern style is the default, so the following line is not needed:
P sh
R /
# can be rebuild
\- /home/*/.cache
# they\(aqre downloads for a reason
\- /home/*/Downloads
# susan is a nice person
# include susans home
+ /home/susan
# don\(aqt backup the other home directories
\- /home/*
.ft P
.fi
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.SH AUTHOR
The Borg Collective
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