mirror of
https://github.com/borgbackup/borg.git
synced 2024-12-26 01:37:20 +00:00
8e8d9d3f48
The former section is a bit older (Nov 2016) and has been the piece responsible for finding CVE-2016-10099, since while writing it I wondered how the manifest was authenticated to actually *be* the manifest. Well. There it is ;) It has been edited to final form only recently and should now be ready for review. The latter section is new.
725 lines
26 KiB
ReStructuredText
725 lines
26 KiB
ReStructuredText
.. include:: global.rst.inc
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.. highlight:: none
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.. _detailed_usage:
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Usage
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=====
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|project_name| consists of a number of commands. Each command accepts
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a number of arguments and options. The following sections will describe each
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command in detail.
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General
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-------
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.. include:: usage_general.rst.inc
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In case you are interested in more details (like formulas), please see
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:ref:`internals`.
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Common options
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++++++++++++++
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All |project_name| commands share these options:
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.. include:: usage/common-options.rst.inc
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.. include:: usage/init.rst.inc
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Examples
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~~~~~~~~
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::
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# Local repository, repokey encryption, BLAKE2b (often faster, since Borg 1.1)
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$ borg init --encryption=repokey-blake2 /path/to/repo
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# Local repository (no encryption)
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$ borg init --encryption=none /path/to/repo
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# Remote repository (accesses a remote borg via ssh)
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$ borg init --encryption=repokey-blake2 user@hostname:backup
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# Remote repository (store the key your home dir)
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$ borg init --encryption=keyfile user@hostname:backup
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.. include:: usage/create.rst.inc
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Examples
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~~~~~~~~
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::
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# Backup ~/Documents into an archive named "my-documents"
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$ borg create /path/to/repo::my-documents ~/Documents
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# same, but list all files as we process them
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$ borg create --list /path/to/repo::my-documents ~/Documents
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# Backup ~/Documents and ~/src but exclude pyc files
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$ borg create /path/to/repo::my-files \
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~/Documents \
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~/src \
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--exclude '*.pyc'
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# Backup home directories excluding image thumbnails (i.e. only
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# /home/*/.thumbnails is excluded, not /home/*/*/.thumbnails)
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$ borg create /path/to/repo::my-files /home \
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--exclude 're:^/home/[^/]+/\.thumbnails/'
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# Do the same using a shell-style pattern
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$ borg create /path/to/repo::my-files /home \
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--exclude 'sh:/home/*/.thumbnails'
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# Backup the root filesystem into an archive named "root-YYYY-MM-DD"
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# use zlib compression (good, but slow) - default is no compression
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$ borg create -C zlib,6 /path/to/repo::root-{now:%Y-%m-%d} / --one-file-system
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# Backup a remote host locally ("pull" style) using sshfs
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$ mkdir sshfs-mount
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$ sshfs root@example.com:/ sshfs-mount
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$ cd sshfs-mount
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$ borg create /path/to/repo::example.com-root-{now:%Y-%m-%d} .
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$ cd ..
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$ fusermount -u sshfs-mount
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# Make a big effort in fine granular deduplication (big chunk management
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# overhead, needs a lot of RAM and disk space, see formula in internals
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# docs - same parameters as borg < 1.0 or attic):
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$ borg create --chunker-params 10,23,16,4095 /path/to/repo::small /smallstuff
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# Backup a raw device (must not be active/in use/mounted at that time)
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$ dd if=/dev/sdx bs=10M | borg create /path/to/repo::my-sdx -
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# No compression (default)
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$ borg create /path/to/repo::arch ~
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# Super fast, low compression
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$ borg create --compression lz4 /path/to/repo::arch ~
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# Less fast, higher compression (N = 0..9)
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$ borg create --compression zlib,N /path/to/repo::arch ~
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# Even slower, even higher compression (N = 0..9)
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$ borg create --compression lzma,N /path/to/repo::arch ~
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# Use short hostname, user name and current time in archive name
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$ borg create /path/to/repo::{hostname}-{user}-{now} ~
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# Similar, use the same datetime format as borg 1.1 will have as default
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$ borg create /path/to/repo::{hostname}-{user}-{now:%Y-%m-%dT%H:%M:%S} ~
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# As above, but add nanoseconds
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$ borg create /path/to/repo::{hostname}-{user}-{now:%Y-%m-%dT%H:%M:%S.%f} ~
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.. include:: usage/extract.rst.inc
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Examples
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~~~~~~~~
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::
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# Extract entire archive
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$ borg extract /path/to/repo::my-files
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# Extract entire archive and list files while processing
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$ borg extract --list /path/to/repo::my-files
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# Verify whether an archive could be successfully extracted, but do not write files to disk
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$ borg extract --dry-run /path/to/repo::my-files
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# Extract the "src" directory
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$ borg extract /path/to/repo::my-files home/USERNAME/src
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# Extract the "src" directory but exclude object files
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$ borg extract /path/to/repo::my-files home/USERNAME/src --exclude '*.o'
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# Restore a raw device (must not be active/in use/mounted at that time)
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$ borg extract --stdout /path/to/repo::my-sdx | dd of=/dev/sdx bs=10M
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.. Note::
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Currently, extract always writes into the current working directory ("."),
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so make sure you ``cd`` to the right place before calling ``borg extract``.
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.. include:: usage/check.rst.inc
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.. include:: usage/rename.rst.inc
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Examples
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~~~~~~~~
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::
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$ borg create /path/to/repo::archivename ~
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$ borg list /path/to/repo
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archivename Mon, 2016-02-15 19:50:19
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$ borg rename /path/to/repo::archivename newname
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$ borg list /path/to/repo
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newname Mon, 2016-02-15 19:50:19
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.. include:: usage/list.rst.inc
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Examples
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~~~~~~~~
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::
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$ borg list /path/to/repo
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Monday Mon, 2016-02-15 19:15:11
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repo Mon, 2016-02-15 19:26:54
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root-2016-02-15 Mon, 2016-02-15 19:36:29
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newname Mon, 2016-02-15 19:50:19
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...
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$ borg list /path/to/repo::root-2016-02-15
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drwxr-xr-x root root 0 Mon, 2016-02-15 17:44:27 .
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drwxrwxr-x root root 0 Mon, 2016-02-15 19:04:49 bin
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-rwxr-xr-x root root 1029624 Thu, 2014-11-13 00:08:51 bin/bash
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lrwxrwxrwx root root 0 Fri, 2015-03-27 20:24:26 bin/bzcmp -> bzdiff
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-rwxr-xr-x root root 2140 Fri, 2015-03-27 20:24:22 bin/bzdiff
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...
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$ borg list /path/to/repo::archiveA --list-format="{mode} {user:6} {group:6} {size:8d} {isomtime} {path}{extra}{NEWLINE}"
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drwxrwxr-x user user 0 Sun, 2015-02-01 11:00:00 .
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drwxrwxr-x user user 0 Sun, 2015-02-01 11:00:00 code
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drwxrwxr-x user user 0 Sun, 2015-02-01 11:00:00 code/myproject
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-rw-rw-r-- user user 1416192 Sun, 2015-02-01 11:00:00 code/myproject/file.ext
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...
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.. include:: usage/diff.rst.inc
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Examples
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~~~~~~~~
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::
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$ borg init -e=none testrepo
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$ mkdir testdir
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$ cd testdir
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$ echo asdf > file1
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$ dd if=/dev/urandom bs=1M count=4 > file2
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$ touch file3
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$ borg create ../testrepo::archive1 .
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$ chmod a+x file1
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$ echo "something" >> file2
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$ borg create ../testrepo::archive2 .
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$ rm file3
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$ touch file4
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$ borg create ../testrepo::archive3 .
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$ cd ..
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$ borg diff testrepo::archive1 archive2
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[-rw-r--r-- -> -rwxr-xr-x] file1
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+135 B -252 B file2
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$ borg diff testrepo::archive2 archive3
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added 0 B file4
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removed 0 B file3
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$ borg diff testrepo::archive1 archive3
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[-rw-r--r-- -> -rwxr-xr-x] file1
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+135 B -252 B file2
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added 0 B file4
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removed 0 B file3
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.. include:: usage/delete.rst.inc
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Examples
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~~~~~~~~
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::
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# delete a single backup archive:
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$ borg delete /path/to/repo::Monday
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# delete the whole repository and the related local cache:
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$ borg delete /path/to/repo
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You requested to completely DELETE the repository *including* all archives it contains:
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repo Mon, 2016-02-15 19:26:54
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root-2016-02-15 Mon, 2016-02-15 19:36:29
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newname Mon, 2016-02-15 19:50:19
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Type 'YES' if you understand this and want to continue: YES
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.. include:: usage/prune.rst.inc
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Examples
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~~~~~~~~
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Be careful, prune is a potentially dangerous command, it will remove backup
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archives.
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The default of prune is to apply to **all archives in the repository** unless
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you restrict its operation to a subset of the archives using ``--prefix``.
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When using ``--prefix``, be careful to choose a good prefix - e.g. do not use a
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prefix "foo" if you do not also want to match "foobar".
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It is strongly recommended to always run ``prune -v --list --dry-run ...``
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first so you will see what it would do without it actually doing anything.
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There is also a visualized prune example in ``docs/misc/prune-example.txt``.
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::
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# Keep 7 end of day and 4 additional end of week archives.
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# Do a dry-run without actually deleting anything.
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$ borg prune -v --list --dry-run --keep-daily=7 --keep-weekly=4 /path/to/repo
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# Same as above but only apply to archive names starting with the hostname
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# of the machine followed by a "-" character:
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$ borg prune -v --list --keep-daily=7 --keep-weekly=4 --prefix='{hostname}-' /path/to/repo
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# Keep 7 end of day, 4 additional end of week archives,
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# and an end of month archive for every month:
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$ borg prune -v --list --keep-daily=7 --keep-weekly=4 --keep-monthly=-1 /path/to/repo
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# Keep all backups in the last 10 days, 4 additional end of week archives,
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# and an end of month archive for every month:
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$ borg prune -v --list --keep-within=10d --keep-weekly=4 --keep-monthly=-1 /path/to/repo
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.. include:: usage/info.rst.inc
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Examples
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~~~~~~~~
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::
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$ borg info /path/to/repo::root-2016-02-15
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Name: root-2016-02-15
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Fingerprint: 57c827621f21b000a8d363c1e163cc55983822b3afff3a96df595077a660be50
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Hostname: myhostname
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Username: root
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Time (start): Mon, 2016-02-15 19:36:29
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Time (end): Mon, 2016-02-15 19:39:26
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Command line: /usr/local/bin/borg create --list -C zlib,6 /path/to/repo::root-2016-02-15 / --one-file-system
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Number of files: 38100
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Original size Compressed size Deduplicated size
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This archive: 1.33 GB 613.25 MB 571.64 MB
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All archives: 1.63 GB 853.66 MB 584.12 MB
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Unique chunks Total chunks
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Chunk index: 36858 48844
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.. include:: usage/mount.rst.inc
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.. include:: usage/umount.rst.inc
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Examples
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~~~~~~~~
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borg mount
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++++++++++
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::
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$ borg mount /path/to/repo::root-2016-02-15 /tmp/mymountpoint
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$ ls /tmp/mymountpoint
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bin boot etc home lib lib64 lost+found media mnt opt root sbin srv tmp usr var
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$ borg umount /tmp/mymountpoint
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::
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$ borg mount -o versions /path/to/repo /tmp/mymountpoint
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$ ls -l /tmp/mymountpoint/home/user/doc.txt/
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total 24
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-rw-rw-r-- 1 user group 12357 Aug 26 21:19 doc.txt.cda00bc9
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-rw-rw-r-- 1 user group 12204 Aug 26 21:04 doc.txt.fa760f28
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$ fusermount -u /tmp/mymountpoint
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borgfs
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++++++
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::
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$ echo '/mnt/backup /tmp/myrepo fuse.borgfs defaults,noauto 0 0' >> /etc/fstab
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$ echo '/mnt/backup::root-2016-02-15 /tmp/myarchive fuse.borgfs defaults,noauto 0 0' >> /etc/fstab
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$ mount /tmp/myrepo
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$ mount /tmp/myarchive
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$ ls /tmp/myrepo
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root-2016-02-01 root-2016-02-2015
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$ ls /tmp/myarchive
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bin boot etc home lib lib64 lost+found media mnt opt root sbin srv tmp usr var
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.. Note::
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``borgfs`` will be automatically provided if you used a distribution
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package, ``pip`` or ``setup.py`` to install |project_name|. Users of the
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standalone binary will have to manually create a symlink (see
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:ref:`pyinstaller-binary`).
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.. include:: usage/key_export.rst.inc
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.. include:: usage/key_import.rst.inc
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.. _borg-change-passphrase:
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.. include:: usage/key_change-passphrase.rst.inc
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Examples
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~~~~~~~~
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::
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# Create a key file protected repository
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$ borg init --encryption=keyfile -v /path/to/repo
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Initializing repository at "/path/to/repo"
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Enter new passphrase:
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Enter same passphrase again:
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Remember your passphrase. Your data will be inaccessible without it.
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Key in "/root/.config/borg/keys/mnt_backup" created.
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Keep this key safe. Your data will be inaccessible without it.
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Synchronizing chunks cache...
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Archives: 0, w/ cached Idx: 0, w/ outdated Idx: 0, w/o cached Idx: 0.
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Done.
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# Change key file passphrase
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$ borg key change-passphrase -v /path/to/repo
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Enter passphrase for key /root/.config/borg/keys/mnt_backup:
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Enter new passphrase:
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Enter same passphrase again:
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Remember your passphrase. Your data will be inaccessible without it.
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Key updated
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Fully automated using environment variables:
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::
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$ BORG_NEW_PASSPHRASE=old borg init -e=repokey repo
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# now "old" is the current passphrase.
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$ BORG_PASSPHRASE=old BORG_NEW_PASSPHRASE=new borg key change-passphrase repo
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# now "new" is the current passphrase.
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.. include:: usage/serve.rst.inc
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Examples
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~~~~~~~~
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borg serve has special support for ssh forced commands (see ``authorized_keys``
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example below): it will detect that you use such a forced command and extract
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the value of the ``--restrict-to-path`` option(s).
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It will then parse the original command that came from the client, makes sure
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that it is also ``borg serve`` and enforce path restriction(s) as given by the
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forced command. That way, other options given by the client (like ``--info`` or
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``--umask``) are preserved (and are not fixed by the forced command).
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::
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# Allow an SSH keypair to only run borg, and only have access to /path/to/repo.
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# Use key options to disable unneeded and potentially dangerous SSH functionality.
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# This will help to secure an automated remote backup system.
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$ cat ~/.ssh/authorized_keys
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command="borg serve --restrict-to-path /path/to/repo",no-pty,no-agent-forwarding,no-port-forwarding,no-X11-forwarding,no-user-rc ssh-rsa AAAAB3[...]
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.. include:: usage/upgrade.rst.inc
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Examples
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~~~~~~~~
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::
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# Upgrade the borg repository to the most recent version.
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$ borg upgrade -v /path/to/repo
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making a hardlink copy in /path/to/repo.upgrade-2016-02-15-20:51:55
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opening attic repository with borg and converting
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no key file found for repository
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converting repo index /path/to/repo/index.0
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converting 1 segments...
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converting borg 0.xx to borg current
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no key file found for repository
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.. _borg_key_migrate-to-repokey:
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Upgrading a passphrase encrypted attic repo
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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attic offered a "passphrase" encryption mode, but this was removed in borg 1.0
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and replaced by the "repokey" mode (which stores the passphrase-protected
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encryption key into the repository config).
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Thus, to upgrade a "passphrase" attic repo to a "repokey" borg repo, 2 steps
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are needed, in this order:
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- borg upgrade repo
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- borg key migrate-to-repokey repo
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.. include:: usage/recreate.rst.inc
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Examples
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~~~~~~~~
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::
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# Make old (Attic / Borg 0.xx) archives deduplicate with Borg 1.x archives
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# Archives created with Borg 1.1+ and the default chunker params are skipped (archive ID stays the same)
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$ borg recreate /mnt/backup --chunker-params default --progress
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# Create a backup with little but fast compression
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$ borg create /mnt/backup::archive /some/files --compression lz4
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# Then compress it - this might take longer, but the backup has already completed, so no inconsistencies
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# from a long-running backup job.
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$ borg recreate /mnt/backup::archive --compression zlib,9
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# Remove unwanted files from all archives in a repository
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$ borg recreate /mnt/backup -e /home/icke/Pictures/drunk_photos
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# Change archive comment
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$ borg create --comment "This is a comment" /mnt/backup::archivename ~
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$ borg info /mnt/backup::archivename
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Name: archivename
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Fingerprint: ...
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Comment: This is a comment
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...
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$ borg recreate --comment "This is a better comment" /mnt/backup::archivename
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$ borg info /mnt/backup::archivename
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Name: archivename
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Fingerprint: ...
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Comment: This is a better comment
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...
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.. include:: usage/with-lock.rst.inc
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.. include:: usage/break-lock.rst.inc
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Miscellaneous Help
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------------------
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.. include:: usage/help.rst.inc
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Debug Commands
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--------------
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There is a ``borg debug`` command that has some subcommands which are all
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**not intended for normal use** and **potentially very dangerous** if used incorrectly.
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For example, ``borg debug put-obj`` and ``borg debug delete-obj`` will only do
|
|
what their name suggests: put objects into repo / delete objects from repo.
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|
|
|
Please note:
|
|
|
|
- they will not update the chunks cache (chunks index) about the object
|
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- they will not update the manifest (so no automatic chunks index resync is triggered)
|
|
- they will not check whether the object is in use (e.g. before delete-obj)
|
|
- they will not update any metadata which may point to the object
|
|
|
|
They exist to improve debugging capabilities without direct system access, e.g.
|
|
in case you ever run into some severe malfunction. Use them only if you know
|
|
what you are doing or if a trusted |project_name| developer tells you what to do.
|
|
|
|
|
|
Additional Notes
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|
----------------
|
|
|
|
Here are misc. notes about topics that are maybe not covered in enough detail in the usage section.
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|
--chunker-params
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
The chunker params influence how input files are cut into pieces (chunks)
|
|
which are then considered for deduplication. They also have a big impact on
|
|
resource usage (RAM and disk space) as the amount of resources needed is
|
|
(also) determined by the total amount of chunks in the repository (see
|
|
`Indexes / Caches memory usage` for details).
|
|
|
|
``--chunker-params=10,23,16,4095`` results in a fine-grained deduplication
|
|
and creates a big amount of chunks and thus uses a lot of resources to manage
|
|
them. This is good for relatively small data volumes and if the machine has a
|
|
good amount of free RAM and disk space.
|
|
|
|
``--chunker-params=19,23,21,4095`` (default) results in a coarse-grained
|
|
deduplication and creates a much smaller amount of chunks and thus uses less
|
|
resources. This is good for relatively big data volumes and if the machine has
|
|
a relatively low amount of free RAM and disk space.
|
|
|
|
If you already have made some archives in a repository and you then change
|
|
chunker params, this of course impacts deduplication as the chunks will be
|
|
cut differently.
|
|
|
|
In the worst case (all files are big and were touched in between backups), this
|
|
will store all content into the repository again.
|
|
|
|
Usually, it is not that bad though:
|
|
|
|
- usually most files are not touched, so it will just re-use the old chunks
|
|
it already has in the repo
|
|
- files smaller than the (both old and new) minimum chunksize result in only
|
|
one chunk anyway, so the resulting chunks are same and deduplication will apply
|
|
|
|
If you switch chunker params to save resources for an existing repo that
|
|
already has some backup archives, you will see an increasing effect over time,
|
|
when more and more files have been touched and stored again using the bigger
|
|
chunksize **and** all references to the smaller older chunks have been removed
|
|
(by deleting / pruning archives).
|
|
|
|
If you want to see an immediate big effect on resource usage, you better start
|
|
a new repository when changing chunker params.
|
|
|
|
For more details, see :ref:`chunker_details`.
|
|
|
|
|
|
--umask
|
|
~~~~~~~
|
|
|
|
If you use ``--umask``, make sure that all repository-modifying borg commands
|
|
(create, delete, prune) that access the repository in question use the same
|
|
``--umask`` value.
|
|
|
|
If multiple machines access the same repository, this should hold true for all
|
|
of them.
|
|
|
|
--read-special
|
|
~~~~~~~~~~~~~~
|
|
|
|
The --read-special option is special - you do not want to use it for normal
|
|
full-filesystem backups, but rather after carefully picking some targets for it.
|
|
|
|
The option ``--read-special`` triggers special treatment for block and char
|
|
device files as well as FIFOs. Instead of storing them as such a device (or
|
|
FIFO), they will get opened, their content will be read and in the backup
|
|
archive they will show up like a regular file.
|
|
|
|
Symlinks will also get special treatment if (and only if) they point to such
|
|
a special file: instead of storing them as a symlink, the target special file
|
|
will get processed as described above.
|
|
|
|
One intended use case of this is backing up the contents of one or multiple
|
|
block devices, like e.g. LVM snapshots or inactive LVs or disk partitions.
|
|
|
|
You need to be careful about what you include when using ``--read-special``,
|
|
e.g. if you include ``/dev/zero``, your backup will never terminate.
|
|
|
|
Restoring such files' content is currently only supported one at a time via
|
|
``--stdout`` option (and you have to redirect stdout to where ever it shall go,
|
|
maybe directly into an existing device file of your choice or indirectly via
|
|
``dd``).
|
|
|
|
To some extent, mounting a backup archive with the backups of special files
|
|
via ``borg mount`` and then loop-mounting the image files from inside the mount
|
|
point will work. If you plan to access a lot of data in there, it likely will
|
|
scale and perform better if you do not work via the FUSE mount.
|
|
|
|
Example
|
|
+++++++
|
|
|
|
Imagine you have made some snapshots of logical volumes (LVs) you want to backup.
|
|
|
|
.. note::
|
|
|
|
For some scenarios, this is a good method to get "crash-like" consistency
|
|
(I call it crash-like because it is the same as you would get if you just
|
|
hit the reset button or your machine would abrubtly and completely crash).
|
|
This is better than no consistency at all and a good method for some use
|
|
cases, but likely not good enough if you have databases running.
|
|
|
|
Then you create a backup archive of all these snapshots. The backup process will
|
|
see a "frozen" state of the logical volumes, while the processes working in the
|
|
original volumes continue changing the data stored there.
|
|
|
|
You also add the output of ``lvdisplay`` to your backup, so you can see the LV
|
|
sizes in case you ever need to recreate and restore them.
|
|
|
|
After the backup has completed, you remove the snapshots again. ::
|
|
|
|
$ # create snapshots here
|
|
$ lvdisplay > lvdisplay.txt
|
|
$ borg create --read-special /path/to/repo::arch lvdisplay.txt /dev/vg0/*-snapshot
|
|
$ # remove snapshots here
|
|
|
|
Now, let's see how to restore some LVs from such a backup. ::
|
|
|
|
$ borg extract /path/to/repo::arch lvdisplay.txt
|
|
$ # create empty LVs with correct sizes here (look into lvdisplay.txt).
|
|
$ # we assume that you created an empty root and home LV and overwrite it now:
|
|
$ borg extract --stdout /path/to/repo::arch dev/vg0/root-snapshot > /dev/vg0/root
|
|
$ borg extract --stdout /path/to/repo::arch dev/vg0/home-snapshot > /dev/vg0/home
|
|
|
|
|
|
.. _append_only_mode:
|
|
|
|
Append-only mode
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
A repository can be made "append-only", which means that Borg will never overwrite or
|
|
delete committed data (append-only refers to the segment files, but borg will also
|
|
reject to delete the repository completely). This is useful for scenarios where a
|
|
backup client machine backups remotely to a backup server using ``borg serve``, since
|
|
a hacked client machine cannot delete backups on the server permanently.
|
|
|
|
To activate append-only mode, edit the repository ``config`` file and add a line
|
|
``append_only=1`` to the ``[repository]`` section (or edit the line if it exists).
|
|
|
|
In append-only mode Borg will create a transaction log in the ``transactions`` file,
|
|
where each line is a transaction and a UTC timestamp.
|
|
|
|
In addition, ``borg serve`` can act as if a repository is in append-only mode with
|
|
its option ``--append-only``. This can be very useful for fine-tuning access control
|
|
in ``.ssh/authorized_keys`` ::
|
|
|
|
command="borg serve --append-only ..." ssh-rsa <key used for not-always-trustable backup clients>
|
|
command="borg serve ..." ssh-rsa <key used for backup management>
|
|
|
|
Example
|
|
+++++++
|
|
|
|
Suppose an attacker remotely deleted all backups, but your repository was in append-only
|
|
mode. A transaction log in this situation might look like this: ::
|
|
|
|
transaction 1, UTC time 2016-03-31T15:53:27.383532
|
|
transaction 5, UTC time 2016-03-31T15:53:52.588922
|
|
transaction 11, UTC time 2016-03-31T15:54:23.887256
|
|
transaction 12, UTC time 2016-03-31T15:55:54.022540
|
|
transaction 13, UTC time 2016-03-31T15:55:55.472564
|
|
|
|
From your security logs you conclude the attacker gained access at 15:54:00 and all
|
|
the backups where deleted or replaced by compromised backups. From the log you know
|
|
that transactions 11 and later are compromised. Note that the transaction ID is the
|
|
name of the *last* file in the transaction. For example, transaction 11 spans files 6
|
|
to 11.
|
|
|
|
In a real attack you'll likely want to keep the compromised repository
|
|
intact to analyze what the attacker tried to achieve. It's also a good idea to make this
|
|
copy just in case something goes wrong during the recovery. Since recovery is done by
|
|
deleting some files, a hard link copy (``cp -al``) is sufficient.
|
|
|
|
The first step to reset the repository to transaction 5, the last uncompromised transaction,
|
|
is to remove the ``hints.N`` and ``index.N`` files in the repository (these two files are
|
|
always expendable). In this example N is 13.
|
|
|
|
Then remove or move all segment files from the segment directories in ``data/`` starting
|
|
with file 6::
|
|
|
|
rm data/**/{6..13}
|
|
|
|
That's all to it.
|
|
|
|
Drawbacks
|
|
+++++++++
|
|
|
|
As data is only appended, and nothing removed, commands like ``prune`` or ``delete``
|
|
won't free disk space, they merely tag data as deleted in a new transaction.
|
|
|
|
Be aware that as soon as you write to the repo in non-append-only mode (e.g. prune,
|
|
delete or create archives from an admin machine), it will remove the deleted objects
|
|
permanently (including the ones that were already marked as deleted, but not removed,
|
|
in append-only mode).
|
|
|
|
Note that you can go back-and-forth between normal and append-only operation by editing
|
|
the configuration file, it's not a "one way trip".
|
|
|
|
Further considerations
|
|
++++++++++++++++++++++
|
|
|
|
Append-only mode is not respected by tools other than Borg. ``rm`` still works on the
|
|
repository. Make sure that backup client machines only get to access the repository via
|
|
``borg serve``.
|
|
|
|
Ensure that no remote access is possible if the repository is temporarily set to normal mode
|
|
for e.g. regular pruning.
|
|
|
|
Further protections can be implemented, but are outside of Borg's scope. For example,
|
|
file system snapshots or wrapping ``borg serve`` to set special permissions or ACLs on
|
|
new data files.
|