1SNAPPER(8) Filesystem Snapshot Management SNAPPER(8)
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6 snapper - Command-line program for filesystem snapshot management
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9 snapper [--global-opts] command [--command-opts] [command-arguments]
10 snapper {--help}
12
14 Snapper is a command-line program for filesystem snapshot management.
15 It can create, delete and compare snapshots and undo changes done
16 between snapshots.
17 Snapper never modifies the content of snapshots. Thus snapper creates
19 read-only snapshots if supported by the kernel. Btrfs and
20 thin-provisioned LVM logical volumes are supported. Some filesystems
21 might not be supported depending on your installation.
22
24 Configurations
25 For each filesystem or subvolume that should be snapshotted by snapper,
26 a configuration file is required, see snapper-configs(5). The setup can
27 be done with the create-config command.
28 Snapshots
30 Snapper distinguishes three types of snapshots.
31 pre
33 Pre snapshots should always have a corresponding post snapshot. The
34 intention of pre/post snapshot pairs is to snapshot the filesystem
35 before and after a modification.
36 post
38 See pre type.
39 single
41 These snapshots have no special relationship to other snapshots.
42 Note that filesystem-wise all three types are the same.
44 Snapshot Description and Userdata
46 With each snapshot a description and some userdata can be associated.
47 The description is a string. The userdata is a list of key-value pairs
48 where the keys and values are strings.
49 Do not use non-ASCII characters for the snapshot description, userdata
51 or any other strings, unless you always use the UTF-8 character
52 encoding.
53 Automatic Snapshot Creation
55 Next to manual snapshot creation, snapshots are also created
56 automatically.
57 • A cron-job creates hourly snapshots.
59 • Certain programs like YaST and zypper create pre/post snapshot
61 pairs when modifying the system.
62 Cleanup Algorithms
64 Snapper provides several algorithms to clean up old snapshots. The
65 algorithms are executed in a daily cron-job. This can be configured in
66 the corresponding configurations files along with parameters for every
67 algorithm.
68 number
70 Deletes old snapshots when a certain number of snapshots is
71 reached.
72 timeline
74 Deletes old snapshots but keeps a number of hourly, daily, weekly,
75 monthly and yearly snapshots.
76 empty-pre-post
78 Deletes pre/post snapshot pairs with empty diffs.
79 The number and timeline cleanup algorithms can also try to keep the
81 space used by snapshots below a limit and the free space of the
82 filesystem above a limit. For the first condition quota must be setup,
83 see command setup-quota. Additional the NUMBER_LIMIT and TIMELINE_LIMIT
84 variables in the config file must have ranges (min- and max-value). The
85 algorithms will then make two passes:
86 1. Delete snapshots above the max-value independent of the snapshot
88 and filesystem space.
89 2. Delete snapshots above the min-value until the limits for the
91 snapshot and filesystem are reached.
92 The limit for the used space can be configured via the SPACE_LIMIT
94 variable. Note: Only snapshots that have a cleanup algorithm set are
95 taken into account when calculating the space used by snapshots. The
96 limit for the free space can be configured via the FREE_LIMIT variable.
97 Filters
99 Some files keep state information of the system, e.g. /etc/mtab. Such
100 files should never be reverted. To help users, snapper allows one to
101 ignore these files.
102 Each line in all files /etc/snapper/filters/*.txt specifies a pattern.
104 When snapper computes the difference between two snapshots it ignores
105 all files and directories matching any of those patterns by using
106 fnmatch(3) with the flag FNM_LEADING_DIR.
107 Note that filters do not exclude files or directories from being
109 snapshotted. For that, use subvolumes or mount points.
110
112 -q, --quiet
113 Suppress normal output. Error messages will still be printed,
114 though.
115 -v, --verbose
117 Increase verbosity.
118 --utc
120 Display dates and times in UTC. By default, local time is used.
121 --iso
123 Display dates and times in ISO format. ISO format is always used
124 for machine-readable outputs.
125 -t, --table-style style
127 Specifies table style. Table style is identified by an integer
128 number.
129 --abbreviate
131 Try to abbreviate texts in some columns so that tables fit the
132 width of the screen.
133 --machine-readable format
135 Specifies a machine-readable output format. Possible options are
136 csv and json.
137 --csvout
139 Sets CSV output format. See RFC 4180[1] for the details, except
140 lines end with a LF, not CR+LF.
141 --jsonout
143 Sets JSON output format.
144 --separator character
146 Specifies the character separator for CSV output format.
147 -c, --config name
149 Use specified configuration instead of the default configuration.
150 The default configuration is named "root".
151 --no-dbus
153 Operate without a DBus connection.
154 Use with caution since a running snapperd will not know about
156 modifications made to the system.
157 -r, --root path
159 Operate on target root. Only works together with no-dbus and only
160 for some commands.
161 -a, --ambit ambit
163 Operate in the specified ambit. Can be used to override the ambit
164 detection. Allowed ambits are auto, classic and transactional.
165 --version
167 Print version and exit.
168
170 Snapper provides a number of commands. Each command accepts the options
171 listed in the GLOBAL OPTIONS section. These options must be specified
172 before the command name. In addition, many commands have specific
173 options, which are listed in this section. These command-specific
174 options must be specified after the name of the command and before any
175 of the command arguments.
176 help
178 Show short help text.
179 list-configs [options]
181 List available configurations.
182 --columns columns
184 Select columns to show separated by comma.
185 Possible columns are: config, subvolume.
187 create-config [options] subvolume
189 Create a new configuration for a filesystem or subvolume. For this
190 command you will likely need the global option --config, see GLOBAL
191 OPTIONS and CONCEPTS.
192 -f, --fstype fstype
194 Manually set filesystem type. Supported values are btrfs and
195 lvm. For lvm, snapper uses LVM thin-provisioned snapshots. The
196 filesystem type on top of LVM must be provided in parentheses,
197 e.g. lvm(xfs).
198 Without this option snapper tries to detect the filesystem.
200 -t, --template name
202 Name of template for the new configuration file.
203 delete-config
205 Delete a configuration for a filesystem or subvolume. For this
206 command you will likely need to global option --config, see GLOBAL
207 OPTIONS and CONCEPTS.
208 get-config [options]
210 Displays the settings of the configuration.
211 --columns columns
213 Select columns to show separated by comma.
214 Possible columns are: key, value.
216 Columns are not selected when JSON format is used.
218 set-config configdata
220 Changes the settings of the configuration. The settings configdata
221 are a list of key-value-pairs separated by spaces and the key and
222 value must be separated by an equal sign, e.g. "NUMBER_CLEANUP=yes
223 NUMBER_LIMIT=10". The value of SUBVOLUME and FSTYPE cannot be
224 changed.
225 list (ls) [options]
227 List snapshots.
228 -t, --type type
230 Selects type of snapshots to list. Possible values are all,
231 single and pre-post.
232 --disable-used-space
234 Disable display of used space.
235 Calculating the used space needs some time. Thus this option
237 can speedup the listing.
238 -a, --all-configs
240 List snapshots from all configs accessible by the user.
241 --columns columns
243 Select columns to show separated by comma.
244 Possible columns are: config, subvolume, number, default,
246 active, date, user, used-space, cleanup, description, userdata,
247 pre-number, post-number, post-date.
248 For each snapshot the output consists of several columns. Some need
250 explanation:
251 #, Pre # and Post #
253 The number of the snapshot.
254 For btrfs the number can be followed by a sign. A "-" indicates
256 that the snapshot is the currently mounted snapshot and a "+"
257 indicates that the snapshot will be mounted next time (It is
258 the btrfs default subvolume). If both conditions apply a "*" is
259 displayed.
260 Used Space
262 For btrfs the exclusive space of the btrfs quota group
263 corresponding to the snapshot.
264 Display of used space is automatically disabled if not
266 available, e.g. quota not enabled on btrfs.
267 create [options]
269 Create a new snapshot.
270 -t, --type type
272 Specifies the type of the new snapshot. Possible values are
273 single, pre and post.
274 --pre-number number
276 For post snapshots the number of the pre snapshot must be
277 provided.
278 -p, --print-number
280 Print number of the created snapshot.
281 -d, --description description
283 Description for the snapshot.
284 -c, --cleanup-algorithm cleanup-algorithm
286 Set the cleanup algorithm for the snapshot.
287 -u, --userdata userdata
289 Set userdata for the snapshot. The key-value pairs must be
290 separated by comma and the key and value must be separated by
291 an equal sign, e.g. requestid=42,user=arthur.
292 --command command
294 Create a pre and post snapshot and run command in between.
295 --read-only
297 Create a read-only snapshot. This is the default.
298 --read-write
300 Create a read-write snapshot.
301 --from number
303 Create a snapshot from the snapshot with the provided number
304 instead of snapshot 0.
305 modify [options] number
307 Modify a snapshot.
308 -d, --description description
310 New description for snapshot.
311 -c, --cleanup-algorithm cleanup-algorithm
313 Set the cleanup algorithm for the snapshot.
314 -u, --userdata userdata
316 Set userdata for the snapshot. The key-value pairs must be
317 separated by comma and the key and value must be separated by
318 an equal sign, e.g. requestid=42,user=arthur.
319 delete (remove|rm) number | number1-number2
321 Delete a snapshot or a range of snapshots.
322 -s, --sync
324 Sync the filesystem after deleting the snapshots. The details
325 depend on the filesystem type.
326 Btrfs normally asynchronously frees space after deleting
328 snapshots. With this option snapper will wait until the space
329 once used by the deleted snapshots is actually available again.
330 Snapshot 0 cannot be deleted. For btrfs the currently mounted
332 snapshot and the snapshot that will be mounted next time (the btrfs
333 default subvolume) can also not be deleted.
334 mount number
336 Mount a snapshot. Not required for all filesystem types.
337 umount number
339 Unmount a snapshot. Not required for all filesystem types.
340 status [options] number1..number2
342 Compare the snapshots number1 and number2. This will show a list of
343 files and directories that have been created, modified or deleted
344 in the time between the two snapshots have been made.
345 -o, --output file
347 Write output to file file.
348 The output consists of a string encoding the status followed by the
350 filename. The characters of the status string are:
351 1. A "+" means the file was created, a "-" means the file was
353 deleted. A "c" means the content of the file has changed and a
354 "t" means the type of the file has changed (e.g. from regular
355 file to directory).
356 2. A "p" means the permissions are have changed.
358 3. An "u" means the user ownership has changed.
360 4. A "g" means the group ownership has changed.
362 5. A "x" means the extended attribute information has changed.
364 6. An "a" means the ACL information has changed.
366 If there is no change a "." is outputted.
368 diff [options] number1..number2 [files]
370 Compare the snapshots number1 and number2. This will show a diff of
371 the content of files and directories that have been created,
372 modified or deleted in the time between the two snapshots have been
373 made.
374 -i, --input file
376 Read files to diff from file file.
377 --diff-cmd command
379 Command used for comparing files. The default is /usr/bin/diff
380 --new-file --unified. The two files to compare are passed as
381 parameters to the command.
382 -x, --extensions options
384 Extra options passed to the diff command.
385 undochange [options] number1..number2 [files]
387 Undo changes done between snapshot number1 and number2.
388 -i, --input file
390 Read files for which to undo changes from file file.
391 rollback [options] [number]
393 Creates two new snapshots and sets the default subvolume. Per
394 default the system boots from the default subvolume of the root
395 filesystem. The exact actions depend on whether a number is
396 provided or not:
397 • Without a number, a first read-only snapshot of the default
399 subvolume is created. A second read-write snapshot of the
400 current system is created. The system is set to boot from the
401 second snapshot.
402 • With a number, a first read-only snapshot of the current system
404 is created. A second read-write snapshot is created of number.
405 The system is set to boot from the second snapshot.
406 Rollback is only supported with btrfs and requires a properly
408 configured system.
409 -p, --print-number
411 Print number of the second created snapshot.
412 -d, --description description
414 Description for the snapshot.
415 -c, --cleanup-algorithm cleanup-algorithm
417 Set the cleanup algorithm for the snapshot.
418 -u, --userdata userdata
420 Set userdata for the snapshot. The key-value pairs must be
421 separated by comma and the key and value must be separated by
422 an equal sign, e.g. requestid=42,user=arthur.
423 The rollback command also sets the description, the cleanup
425 algorithm and some userdata unless the values are specified on the
426 command line. This will automate cleanup of snapshots created by
427 rollbacks.
428 In other ambits than classic the rollback command does what is
430 required to do a rollback. Anyway it is recommended to use specific
431 programs in that case.
432 setup-quota
434 Sets up quota. Currently only supported with btrfs.
435 cleanup [options] cleanup-algorithm
437 Run the cleanup algorithm cleanup-algorithm. Currently implemented
438 cleanup algorithms are number, timeline and empty-pre-post. To run
439 all cleanup algorithms, all can be provided as cleanup-algorithm.
440 --path path
442 Cleanup all configs affecting path. Only useful for btrfs.
443 --free-space free-space
445 Try to make free-space available. Only useful for btrfs.
446 xadiff number1..number2 [files]
448 Compare the extended attributes between snapshot number1 and
449 number2. See examples below:
450 • +:user.foo for created attributes
452 • -:user.bar for removed attributes
454 • -+:security.selinux for modified attributes
456
458 Non-root users can be allowed to use a configuration by setting
459 ALLOW_USERS or ALLOW_GROUPS in the config file. For all operations to
460 work, the user must also be able to read and access the .snapshots
461 directory inside the subvolume. The .snapshots directory must be owned
462 by root and must not be writable by anybody else.
463 Here are some methods how to achieve that:
465 • Make the directory accessible for everyone:
467 chmod a+rx .snapshots
469 • Make the directory accessible for a group the user belongs to,
471 e.g.:
472 chown :users .snapshots
474 • Make the directory accessible for the user using ACLs, e.g.:
476 setfacl -m u:tux:rx .snapshots
478 The last method can be performed by snapper, see the SYNC_ACL setting
480 in snapper-configs(5).
481
483 /etc/sysconfig/snapper
484 Global configuration file.
485 /etc/snapper/configs
487 Directory containing configuration files.
488 /etc/snapper/config-templates
490 Directory containing configuration templates.
491 /etc/snapper/filters/*.txt
493 Filter files.
494 /var/log/snapper.log
496 Logfile. Please include this file in bug reports.
497
499 There is no mechanism to ensure consistency of the files while a
500 snapshot it made. E.g. the files of a database can be inconsistent
501 while the database is running.
502 Consistency after undochange is not guaranteed. E.g. when the creation
504 of a user is undone, there might still exist files from that user.
505 Support for individual filesystems, rollback and extended attributes
507 are compile-time options and may not be available.
508
510 http://snapper.io/
511
513 Arvin Schnell <aschnell@suse.com>
514
516 snapper-configs(5), snapper-zypp-plugin(8), pam_snapper(8), btrfs(8),
517 lvm(8), attr(5), acl(5)
518
520 1. RFC 4180
521 https://tools.ietf.org/html/rfc4180
5220.8.16 2020-06-15 SNAPPER(8)