borg/docs/man/borg-create.1

.\" Man page generated from reStructuredText
.\" by the Docutils 0.22.4 manpage writer.
.
.
.nr rst2man-indent-level 0
.
.de1 rstReportMargin
\\$1 \\n[an-margin]
level \\n[rst2man-indent-level]
level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
-
\\n[rst2man-indent0]
\\n[rst2man-indent1]
\\n[rst2man-indent2]
..
.de1 INDENT
.\" .rstReportMargin pre:
. RS \\$1
. nr rst2man-indent\\n[rst2man-indent-level] \\n[an-margin]
. nr rst2man-indent-level +1
.\" .rstReportMargin post:
..
.de UNINDENT
. RE
.\" indent \\n[an-margin]
.\" old: \\n[rst2man-indent\\n[rst2man-indent-level]]
.nr rst2man-indent-level -1
.\" new: \\n[rst2man-indent\\n[rst2man-indent-level]]
.in \\n[rst2man-indent\\n[rst2man-indent-level]]u
..
.TH "borg-create" "1" "2026-08-29" "" "borg backup tool"
.SH Name
borg-create \- Creates a new archive.
.SH SYNOPSIS
.sp
borg [common options] create [options] NAME [PATH...]
.SH DESCRIPTION
.sp
This command creates a backup archive containing all files found while recursively
traversing all specified paths. Paths are added to the archive as they are given,
which means that if relative paths are desired, the command must be run from the correct
directory.
.sp
The slashdot hack in paths (recursion roots) is triggered by using \fB/./\fP:
\fB/this/gets/stripped/./this/gets/archived\fP means to process that fs object, but
strip the prefix on the left side of \fB\&./\fP from the archived items (in this case,
\fBthis/gets/archived\fP will be the path in the archived item).
.sp
If a recursion root (a path given on the command line or in a patterns file) is a
symlink, borg follows it and archives what it points to \- using the path you gave.
If \fBcurrent\fP is a symlink pointing to the directory \fB20260801\-2345\fP,
\fBborg create ARCHIVE current\fP thus archives \fBcurrent\fP as a directory (with the
metadata of \fB20260801\-2345\fP) and recurses into it, archiving the contained fs
objects as \fBcurrent/...\fP\&. As the archived paths do not change when the symlink
target changes, the files cache keeps working for such backups.
.sp
Note that the symlink itself is then not in the archive (and neither is its target
path), so restoring will create a real directory (or file) where the symlink was.
If you want the symlink archived as a symlink, do not give it as a recursion root,
but let borg find it while recursing (symlinks found that way are never followed).
A recursion root that is a symlink with a non\-existing target is skipped with a warning.
.sp
If you give both a symlink and its target as recursion roots, borg archives the fs
objects only once, under the path given first (like for any other root given twice).
.sp
When specifying \(aq\-\(aq as a path, borg will read data from standard input and create a
file named \(aqstdin\(aq in the created archive from that data. In some cases, it is more
appropriate to use \-\-content\-from\-command. See the section
\fIReading backup data from stdin\fP below for details.
.sp
The archive will consume almost no disk space for files or parts of files that
have already been stored in other archives.
.sp
The \fB\-\-tags\fP option can be used to add a list of tags to the new archive.
.sp
The archive name does not need to be unique; you can and should use the same
name for a series of archives. The unique archive identifier is its ID (hash),
and you can abbreviate the ID as long as it is unique.
.sp
In the archive name, you may use the following placeholders:
{now}, {utcnow}, {fqdn}, {hostname}, {user} and some others.
.sp
Backup speed is increased by not reprocessing files that are already part of
existing archives and were not modified. The detection of unmodified files is
done by comparing multiple file metadata values with previous values kept in
the files cache.
.sp
This comparison can operate in different modes as given by \fB\-\-files\-cache\fP:
.INDENT 0.0
.IP \(bu 2
ctime,size,inode (default on POSIX systems)
.IP \(bu 2
mtime,size,inode (default on Windows)
.IP \(bu 2
ctime,size (ignore the inode number)
.IP \(bu 2
mtime,size (ignore the inode number)
.IP \(bu 2
rechunk,ctime (all files are considered modified \- rechunk, cache ctime)
.IP \(bu 2
rechunk,mtime (all files are considered modified \- rechunk, cache mtime)
.IP \(bu 2
disabled (disable the files cache, all files considered modified \- rechunk)
.UNINDENT
.sp
inode number: better safety, but often unstable on network filesystems
.sp
Normally, detecting file modifications will take inode information into
consideration to improve the reliability of file change detection.
This is problematic for files located on sshfs and similar network file
systems which do not provide stable inode numbers, such files will always
be considered modified. You can use modes without \fIinode\fP in this case to
improve performance, but reliability of change detection might be reduced.
.sp
ctime vs. mtime: safety vs. speed
.INDENT 0.0
.IP \(bu 2
ctime is a rather safe way to detect changes to a file (metadata and contents)
as it cannot be set from userspace. But a metadata\-only change will already
update the ctime, so there might be some unnecessary chunking/hashing even
without content changes. Some filesystems do not support ctime (change time).
E.g. doing a chown or chmod to a file will change its ctime.
.IP \(bu 2
mtime usually works and only updates if file contents were changed. But mtime
can be arbitrarily set from userspace, e.g., to set mtime back to the same value
it had before a content change happened. This can be used maliciously as well as
well\-meant, but in both cases mtime\-based cache modes can be problematic.
.UNINDENT
.sp
On Windows, ctime is the file \fIcreation\fP time, not the \(dqmetadata change time\(dq it is
on POSIX systems. A ctime based mode would therefore not notice content changes of a
file that keeps its size and inode number, so borg defaults to \fBmtime,size,inode\fP
there. If a ctime based mode is given explicitly on Windows, borg warns and uses the
corresponding mtime based mode instead: ctime,size,inode \-> mtime,size,inode,
ctime,size \-> mtime,size, rechunk,ctime \-> rechunk,mtime.
.INDENT 0.0
.TP
.B The \fB\-\-files\-changed\fP option controls how Borg detects if a file has changed during backup:
.INDENT 7.0
.IP \(bu 2
ctime (default on POSIX): Use ctime to detect changes. This is the safest option.
Not supported on Windows (ctime is file creation time there).
.IP \(bu 2
mtime (default on Windows): Use mtime to detect changes.
.IP \(bu 2
disabled: Disable the \(dqfile has changed while we backed it up\(dq detection completely.
This is not recommended unless you know what you\(aqre doing, as it could lead to
inconsistent backups if files change during the backup process.
.UNINDENT
.UNINDENT
.sp
The mount points of filesystems or filesystem snapshots should be the same for every
creation of a new archive to ensure fast operation. This is because the file cache that
is used to determine changed files quickly uses absolute filenames.
If this is not possible, consider creating a bind mount to a stable location.
.sp
The \fB\-\-progress\fP option shows (from left to right) Original and (uncompressed)
deduplicated size (O and U respectively), then the Number of files (N) processed so far,
followed by the currently processed path.
.sp
Sizes of GB and above are shown with enough decimal places that even MB\-sized progress
stays visible. On a terminal, this needs a width of at least 110 columns \- on narrower
terminals, the compact format is used, so that the path stays readable. If the output
does not go to a terminal (e.g. into a logfile), the precise format is always used.
.sp
When using \fB\-\-stats\fP, you will get some statistics about how much data was
added \- the \(dqThis Archive\(dq deduplicated size there is most interesting as that is
how much your repository will grow. Please note that the \(dqAll archives\(dq stats refer to
the state after creation.
.sp
When \fB\-\-stats\fP is used together with \fB\-\-dry\-run\fP, only the number of files and the
original size are reported. They are computed from file system metadata, without reading
the file contents, so a dry run stays fast. As data is not actually read, chunked, and
deduplicated during a dry run, the deduplicated size is unknown. The sizes of data read
from standard input, from a command\(aqs output, or from special files (\fB\-\-read\-special\fP)
are also unknown in a dry run and counted as zero.
.sp
The \fB\-\-stats\fP output also reports the store statistics (lines prefixed with
\(dqStore\(dq), taken from the storage layer after this run. These cover the backend and
the local store cache: call counts and timings per operation, the load/store data
volumes and throughput, and cache hits/misses. \(dqStore backend load volume\(dq and
\(dqStore backend store volume\(dq are the bytes actually read from and sent to the
backend; a load counts only what missed the cache, and a store counts chunk data
together with Borg\(aqs own index and metadata writes. The values are approximate
because of write buffering and caching. On a repeated backup a near\-zero store
volume means almost no new data had to be written, because the chunks already exist
in the repository (deduplication).
.sp
The \(dqAdded\(dq, \(dqModified\(dq and \(dqUnchanged\(dq file counters come from the files\-cache
comparison described above: \(dqUnchanged\(dq files matched the cached metadata and were
not read again (their existing chunks are reused); \(dqAdded\(dq and \(dqModified\(dq files did
not match and were read and chunked (new chunks are stored, already\-known chunks are
deduplicated). The comparison uses the files cache, keyed by the file\(aqs absolute path.
.sp
For more help on include/exclude patterns, see the \fIborg_patterns\fP command output.
.sp
For more help on placeholders, see the \fIborg_placeholders\fP command output.
.SH OPTIONS
.sp
See \fIborg\-common(1)\fP for common options of Borg commands.
.SS arguments
.INDENT 0.0
.TP
.B NAME
specify the archive name
.TP
.B PATH
paths to archive
.UNINDENT
.SS options
.INDENT 0.0
.TP
.B  \-n\fP,\fB  \-\-dry\-run
do not create a backup archive
.TP
.B  \-s\fP,\fB  \-\-stats
print statistics for the created archive
.TP
.B  \-\-list
output a verbose list of items (files, dirs, ...)
.TP
.BI \-\-filter \ STATUSCHARS
only display items with the given status characters (see description)
.TP
.B  \-\-json
output stats as JSON. Implies \fB\-\-stats\fP\&.
.TP
.BI \-\-stdin\-name \ NAME
use NAME in archive for stdin data (default: \(aqstdin\(aq)
.TP
.BI \-\-stdin\-user \ USER
set user USER in archive for stdin data (default: do not store user/uid)
.TP
.BI \-\-stdin\-group \ GROUP
set group GROUP in archive for stdin data (default: do not store group/gid)
.TP
.BI \-\-stdin\-mode \ M
set mode to M in archive for stdin data (default: 0660)
.TP
.B  \-\-content\-from\-command
interpret PATH as a command and store its stdout. See also the section \(aqReading backup data from stdin\(aq below.
.TP
.B  \-\-paths\-from\-stdin
read DELIM\-separated list of paths to back up from stdin. All control is external: it will back up all files given \- no more, no less.
.TP
.B  \-\-paths\-from\-command
interpret PATH as command and treat its output as \fB\-\-paths\-from\-stdin\fP
.TP
.B  \-\-paths\-from\-shell\-command
interpret PATH as shell command and treat its output as \fB\-\-paths\-from\-stdin\fP
.TP
.BI \-\-paths\-delimiter \ DELIM
set path delimiter for \fB\-\-paths\-from\-stdin\fP, \fB\-\-paths\-from\-command\fP and \fB\-\-paths\-from\-shell\-command\fP (default: \fB\en\fP)
.UNINDENT
.SS Include/Exclude options
.INDENT 0.0
.TP
.BI \-e \ PATTERN\fR,\fB \ \-\-exclude \ PATTERN
exclude paths matching PATTERN
.TP
.BI \-\-exclude\-from \ EXCLUDEFILE
read exclude patterns from EXCLUDEFILE, one per line
.TP
.BI \-\-pattern \ PATTERN
include/exclude paths matching PATTERN
.TP
.BI \-\-patterns\-from \ PATTERNFILE
read include/exclude patterns from PATTERNFILE, one per line
.TP
.B  \-\-exclude\-caches
exclude directories that contain a CACHEDIR.TAG file (\%<https://\:www\:.bford\:.info/\:cachedir/\:spec\:.html>)
.TP
.BI \-\-exclude\-if\-present \ NAME
exclude directories that are tagged by containing a filesystem object with the given NAME
.TP
.B  \-\-keep\-exclude\-tags
if tag objects are specified with \fB\-\-exclude\-if\-present\fP, do not omit the tag objects themselves from the backup archive
.TP
.B  \-\-exclude\-dataless
exclude files flagged DATALESS (macOS: placeholder files whose content is not materialized locally, e.g. not\-downloaded cloud storage files)
.UNINDENT
.SS Filesystem options
.INDENT 0.0
.TP
.B  \-x\fP,\fB  \-\-one\-file\-system
stay in the same file system and do not store mount points of other file systems \- this might behave different from your expectations, see the description below.
.TP
.B  \-\-numeric\-ids
only store numeric user and group identifiers
.TP
.B  \-\-atime
do store atime into archive
.TP
.B  \-\-noctime
do not store ctime into archive
.TP
.B  \-\-nobirthtime
do not store birthtime (creation date) into archive
.TP
.B  \-\-noflags
do not read and store flags (e.g. NODUMP, IMMUTABLE) into archive
.TP
.B  \-\-noacls
do not read and store ACLs into archive
.TP
.B  \-\-noxattrs
do not read and store xattrs into archive
.TP
.B  \-\-sparse
detect sparse holes in input and seek over them instead of reading them
.TP
.BI \-\-digests \ ALGOS
compute these hash digests over the full content of each file and store them into the archive items. Comma\-separated list of hash algorithm names, e.g. \(dqblake3\(dq, or \(dqnone\(dq. default: none
.TP
.BI \-\-files\-cache \ MODE
operate files cache in MODE. default: ctime,size,inode (on Windows: mtime,size,inode, because ctime is file creation time there).
.TP
.BI \-\-files\-changed \ MODE
specify how to detect if a file has changed during backup (ctime, mtime, disabled). default: ctime (on Windows: mtime, because ctime is file creation time there).
.TP
.B  \-\-read\-special
open and read block and char device files as well as FIFOs as if they were regular files. Also follows symlinks pointing to these kinds of files.
.TP
.BI \-\-read\-special\-timeout \ SECONDS
when reading from FIFOs or character devices (see \-\-read\-special): skip the file with an error if no data arrives for more than SECONDS (this includes waiting for a FIFO\(aqs writer to connect). Give 0 to wait forever. default: 1800 seconds.
.TP
.BI \-\-map \ MAPFILE
give a map file describing the content ranges of the (single) input file, so borg does not need to read all of it. See the \fIInput maps\fP section below.
.TP
.BI \-\-reuse\-from \ ARCHIVE
reuse the chunks of this reference archive for the input map\(aqs \fBsame\fP ranges (requires \-\-map). See the \fIInput maps\fP section below.
.TP
.BI \-\-reuse\-path \ PATH
archive\-internal path of the reference item in the \-\-reuse\-from archive (only needed if that archive contains more than one file item).
.UNINDENT
.SS Archive options
.INDENT 0.0
.TP
.BI \-\-comment \ COMMENT
add a comment text to the archive
.TP
.BI \-\-timestamp \ TIMESTAMP
manually specify the archive creation date/time (yyyy\-mm\-ddThh:mm:ss[(+|\-)HH:MM] format, (+|\-)HH:MM is the UTC offset, default: local time zone). Alternatively, give a reference file/directory.
.TP
.BI \-\-chunker\-params \ PARAMS
specify the chunker parameters (ALGO, CHUNK_MIN_EXP, CHUNK_MAX_EXP, HASH_MASK_BITS, NC_LEVEL). default: fastcdc,19,23,21,2
.TP
.BI \-C \ COMPRESSION\fR,\fB \ \-\-compression \ COMPRESSION
select compression algorithm, see the output of the \(dqborg help compression\(dq command for details.
.TP
.BI \-\-tags \ TAG
add tags to archive (comma\-separated or multiple arguments)
.UNINDENT
.SH EXAMPLES
.sp
\fBNote:\fP
.INDENT 0.0
.INDENT 3.5
Archive series and performance: In Borg 2, archives that share the same NAME form an \(dqarchive series\(dq.
The files cache is maintained per series. For best performance on repeated backups, reuse the same
NAME every time you run \fBborg create\fP for the same dataset (e.g. always use \fBmy\-documents\fP).
Frequently changing the NAME (for example by embedding date/time like \fBmy\-documents\-2025\-11\-10\fP)
prevents cache reuse and forces Borg to re\-scan and re\-chunk files, which can make incremental
backups vastly slower. Only vary the NAME if you intentionally want to start a new series.
.sp
If you must vary the archive name but still want cache reuse across names, see the advanced
knobs described in \fIupgradenotes2\fP (\fBBORG_FILES_CACHE_SUFFIX\fP and \fBBORG_FILES_CACHE_TTL\fP),
but the recommended approach is to keep a stable NAME per series.
.UNINDENT
.UNINDENT
.INDENT 0.0
.INDENT 3.5
.sp
.EX
# Backup ~/Documents into an archive named \(dqmy\-documents\(dq
$ borg create my\-documents ~/Documents

# same, but list all files as we process them
$ borg create \-\-list my\-documents ~/Documents

# Backup /mnt/disk/docs, but strip path prefix using the slashdot hack
$ borg create \-\-repo /path/to/repo docs /mnt/disk/./docs

# Backup ~/Documents and ~/src but exclude pyc files
$ borg create my\-files                \e
    ~/Documents                       \e
    ~/src                             \e
    \-\-exclude \(aq*.pyc\(aq

# Backup home directories excluding image thumbnails (i.e. only
# /home/<one directory>/.thumbnails is excluded, not /home/*/*/.thumbnails etc.)
$ borg create my\-files /home \-\-exclude \(aqsh:home/*/.thumbnails\(aq

# Back up the root filesystem into an archive named \(dqroot\-archive\(dq
# Use zlib compression (good, but slow) — default is LZ4 (fast, low compression ratio)
$ borg create \-C zlib,6 \-\-one\-file\-system root\-archive /

# Backup into an archive name like FQDN\-root
$ borg create \(aq{fqdn}\-root\(aq /

# Back up a remote host locally (\(dqpull\(dq style) using SSHFS
$ mkdir sshfs\-mount
$ sshfs root@example.com:/ sshfs\-mount
$ cd sshfs\-mount
$ borg create example.com\-root .
$ cd ..
$ fusermount \-u sshfs\-mount

# Make a big effort in fine\-grained deduplication (big chunk management
# overhead, needs a lot of RAM and disk space; see the formula in the internals docs):
$ borg create \-\-chunker\-params fastcdc,10,23,16,2 small /smallstuff

# Backup a raw device (must not be active/in use/mounted at that time)
$ borg create \-\-read\-special \-\-chunker\-params fixed,4194304 my\-sdx /dev/sdX

# Backup a sparse disk image (must not be active/in use/mounted at that time)
$ borg create \-\-sparse \-\-chunker\-params fixed,4194304 my\-disk my\-disk.raw

# No compression (none)
$ borg create \-\-compression none arch ~

# Super fast, low compression (lz4, default)
$ borg create arch ~

# Less fast, higher compression (zlib, N = 0..9)
$ borg create \-\-compression zlib,N arch ~

# Even slower, even higher compression (lzma, N = 0..9)
$ borg create \-\-compression lzma,N arch ~

# Only compress compressible data with lzma,N (N = 0..9)
$ borg create \-\-compression auto,lzma,N arch ~

# Use the short hostname and username as the archive name
$ borg create \(aq{hostname}\-{user}\(aq ~

# Back up relative paths by moving into the correct directory first
$ cd /home/user/Documents
# The root directory of the archive will be \(dqprojectA\(dq
$ borg create \(aqdaily\-projectA\(aq projectA

# Use external command to determine files to archive
# Use \-\-paths\-from\-stdin with find to back up only files less than 1 MB in size
$ find ~ \-size \-1000k | borg create \-\-paths\-from\-stdin small\-files\-only
# Use \-\-paths\-from\-command with find to back up files from only a given user
$ borg create \-\-paths\-from\-command joes\-files \-\- find /srv/samba/shared \-user joe
# Use \-\-paths\-from\-shell\-command with find to back up a few files from only a given user \-
# BE VERY CAREFUL AND ONLY USE TRUSTED INPUT FOR THE SHELL COMMAND!
$ borg create \-\-paths\-from\-shell\-command some\-of\-joes\-files \-\- \(dqfind /srv/samba/shared \-user joe | head\(dq
# Use \-\-paths\-from\-stdin with \-\-paths\-delimiter (for example, for filenames with newlines in them)
$ find ~ \-size \-1000k \-print0 | borg create \e
    \-\-paths\-from\-stdin \e
    \-\-paths\-delimiter \(dq\e0\(dq \e
    smallfiles\-handle\-newline
.EE
.UNINDENT
.UNINDENT
.SH NOTES
.sp
The \fB\-\-exclude\fP patterns are not like tar. In tar \fB\-\-exclude\fP .bundler/gems will
exclude foo/.bundler/gems. In borg it will not, you need to use \fB\-\-exclude\fP
\(aq*/.bundler/gems\(aq to get the same effect.
.sp
In addition to using \fB\-\-exclude\fP patterns, it is possible to use
\fB\-\-exclude\-if\-present\fP to specify the name of a filesystem object (e.g. a file
or folder name) which, when contained within another folder, will prevent the
containing folder from being backed up.  By default, the containing folder and
all of its contents will be omitted from the backup.  If, however, you wish to
only include the objects specified by \fB\-\-exclude\-if\-present\fP in your backup,
and not include any other contents of the containing folder, this can be enabled
through using the \fB\-\-keep\-exclude\-tags\fP option.
.sp
The \fB\-x\fP or \fB\-\-one\-file\-system\fP option excludes directories, that are mountpoints (and everything in them).
It detects mountpoints by comparing the device number from the output of \fBstat()\fP of the directory and its
parent directory. Specifically, it excludes directories for which \fBstat()\fP reports a device number different
from the device number of their parent.
In general: be aware that there are directories with device number different from their parent, which the kernel
does not consider a mountpoint and also the other way around.
Linux examples for this are bind mounts (possibly same device number, but always a mountpoint) and ALL
subvolumes of a btrfs (different device number from parent but not necessarily a mountpoint).
macOS examples are the apfs mounts of a typical macOS installation.
Therefore, when using \fB\-\-one\-file\-system\fP, you should double\-check that the backup works as intended.
.SS Item flags
.sp
\fB\-\-list\fP outputs a list of all files, directories and other
file system items it considered (no matter whether they had content changes
or not). For each item, it prefixes a single\-letter flag that indicates type
and/or status of the item.
.sp
If you are interested only in a subset of that output, you can give e.g.
\fB\-\-filter=AME\fP and it will only show regular files with A, M or E status (see
below).
.sp
A uppercase character represents the status of a regular file relative to the
\(dqfiles\(dq cache (not relative to the repo \-\- this is an issue if the files cache
is not used). Metadata is stored in any case and for \(aqA\(aq and \(aqM\(aq also new data
chunks are stored. For \(aqU\(aq all data chunks refer to already existing chunks.
.INDENT 0.0
.IP \(bu 2
\(aqA\(aq = regular file, added (see also \fIa_status_oddity\fP in the FAQ)
.IP \(bu 2
\(aqM\(aq = regular file, modified
.IP \(bu 2
\(aqU\(aq = regular file, unchanged
.IP \(bu 2
\(aqC\(aq = regular file, it changed while we backed it up
.IP \(bu 2
\(aqE\(aq = regular file, an error happened while accessing/reading \fIthis\fP file
.UNINDENT
.sp
A lowercase character means a file type other than a regular file,
borg usually just stores their metadata:
.INDENT 0.0
.IP \(bu 2
\(aqd\(aq = directory
.IP \(bu 2
\(aqb\(aq = block device
.IP \(bu 2
\(aqc\(aq = char device
.IP \(bu 2
\(aqh\(aq = regular file, hard link (to already seen inodes)
.IP \(bu 2
\(aqs\(aq = symlink
.IP \(bu 2
\(aqf\(aq = fifo
.UNINDENT
.sp
Other flags used include:
.INDENT 0.0
.IP \(bu 2
\(aq+\(aq = included, item would be backed up (if not in dry\-run mode)
.IP \(bu 2
\(aq\-\(aq = excluded, item would not be / was not backed up
.IP \(bu 2
\(aqi\(aq = backup data was read from standard input (stdin)
.IP \(bu 2
\(aqx\(aq = skipped due to \fB\-\-exclude\-dataless\fP (file is flagged DATALESS)
.IP \(bu 2
\(aq?\(aq = missing status code (if you see this, please file a bug report!)
.UNINDENT
.SS Errors and (incomplete) archives
.sp
If an error happens during archive creation (e.g. some file could not be read
due to a permission error or some other OS error), borg will log a warning or
an error (depending on the type of issue) and continue with the next item.
.sp
At the end of the backup, if there were any such issues, borg will exit with
a non\-zero exit code (usually 1 for warnings).
.sp
\fBThe archive is still saved even if warnings or errors occurred\fP, but it will
only contain the data borg was able to read successfully.
.sp
You should always check the backup logs and the exit code of the borg command.
.SS Reading backup data from stdin
.sp
There are two methods to read from stdin. Either specify \fB\-\fP as path and
pipe directly to borg:
.INDENT 0.0
.INDENT 3.5
.sp
.EX
backup\-vm \-\-id myvm \-\-stdout | borg create \-\-repo REPO ARCHIVE \-
.EE
.UNINDENT
.UNINDENT
.sp
Or use \fB\-\-content\-from\-command\fP to have Borg manage the execution of the
command and piping. If you do so, the first PATH argument is interpreted
as command to execute and any further arguments are treated as arguments
to the command:
.INDENT 0.0
.INDENT 3.5
.sp
.EX
borg create \-\-content\-from\-command \-\-repo REPO ARCHIVE \-\- backup\-vm \-\-id myvm \-\-stdout
.EE
.UNINDENT
.UNINDENT
.sp
\fB\-\-\fP is used to ensure \fB\-\-id\fP and \fB\-\-stdout\fP are \fBnot\fP considered
arguments to \fBborg\fP but rather \fBbackup\-vm\fP\&.
.sp
The difference between the two approaches is that piping to borg creates an
archive even if the command piping to borg exits with a failure. In this case,
\fBone can end up with truncated output being backed up\fP\&. Using
\fB\-\-content\-from\-command\fP, in contrast, borg is guaranteed to fail without
creating an archive should the command fail. The command is considered failed
when it returned a non\-zero exit code.
.sp
Reading from stdin yields just a stream of data without file metadata
associated with it, and the files cache is not needed at all. So it is
safe to disable it via \fB\-\-files\-cache disabled\fP and speed up backup
creation a bit.
.sp
By default, the content read from stdin is stored in a file called \(aqstdin\(aq.
Use \fB\-\-stdin\-name\fP to change the name.
.SS Input maps
.sp
Usually, borg reads the complete input to determine its contents. If you already
know the contents of parts of the input from an external source of truth, you can
give that information via \fB\-\-map MAPFILE\fP and borg will not read the known parts.
The primary use case is backing up snapshots of large block devices (e.g. LVM thin
volumes), where the storage layer knows which ranges are in use.
.sp
The map file must describe the whole input: one range per line, in the form
\fBSTART LENGTH STATE\fP (byte values, decimal or 0x\-prefixed hexadecimal). The
ranges must be sorted, non\-overlapping and contiguous, starting at offset 0 and
covering the exact input size. \fB#\fP starts a comment, empty lines are ignored.
STATE is one of:
.INDENT 0.0
.IP \(bu 2
\fBdata\fP: the range\(aqs contents are read and backed up.
.IP \(bu 2
\fBzero\fP: the range is known to read as all\-zero bytes. borg stores a hole
(all\-zero range) of that size without reading the range.
.IP \(bu 2
\fBsame\fP: the range is known to be identical to the same range of the input
backed up in the \fB\-\-reuse\-from REFARCHIVE\fP reference archive (usually: the
previous backup of an earlier snapshot of the same device). borg reuses the
reference archive\(aqs chunks for such ranges without reading them. This state
requires \fB\-\-reuse\-from\fP\&.
.UNINDENT
.sp
\fBThe map is trusted\fP: if it is wrong (e.g. a range marked \fBzero\fP actually
contains data, or a range marked \fBsame\fP actually changed), the archive will
not match the input and borg cannot detect that. Independently verify the
source producing the maps, and consider doing a periodic full read backup
(without \fB\-\-map\fP).
.sp
For LVM thin volume snapshots, maps can be generated from \fBthin_dump\fP /
\fBthin_delta\fP XML with the \fBscripts/lvm\-thin\-map.py\fP converter from the
borg sources; its docstring shows the complete workflow.
.sp
\fB\-\-map\fP requires giving exactly one input path, which must be a regular file or
(with \fB\-\-read\-special\fP) a block device.
.sp
The reference archive must contain exactly one file item; if it contains more,
select the reference item with \fB\-\-reuse\-path PATH\fP (its archive\-internal path).
Reference chunks that only partially overlap \fBsame\fP ranges are re\-read from
the input, so any chunker gives correct results \- but a fixed block size chunker
(e.g. \fB\-\-chunker\-params fixed,4194304\fP, same parameters as used for the
reference archive) avoids re\-reading at the edges of changed ranges and gives
stable chunk boundaries across backups.
.SS Feeding all file paths from externally
.sp
Usually, you give a starting path (recursion root) to borg and then borg
automatically recurses, finds and backs up all fs objects contained in
there (optionally considering include/exclude rules).
.sp
If you need more control and you want to give every single fs object path
to borg (maybe implementing your own recursion or your own rules), you can use
\fB\-\-paths\-from\-stdin\fP, \fB\-\-paths\-from\-command\fP or \fB\-\-paths\-from\-shell\-command\fP
(with the latter two, borg will fail to create an archive should the command fail).
.sp
Borg supports paths with the slashdot hack to strip path prefixes here also.
So, be careful not to unintentionally trigger that.
.sp
Symlinks given this way are never followed (unlike recursion roots are), they are
archived as symlinks.
.SH SEE ALSO
.sp
\fIborg\-common(1)\fP, \fIborg\-delete(1)\fP, \fIborg\-prune(1)\fP, \fIborg\-check(1)\fP, \fIborg\-patterns(1)\fP, \fIborg\-placeholders(1)\fP, \fIborg\-compression(1)\fP, \fIborg\-repo\-create(1)\fP
.SH Author
The Borg Collective
.\" End of generated man page.