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SNAPPER(8) | Filesystem Snapshot Management | SNAPPER(8) |
NAME¶
snapper - Command-line program for filesystem snapshot managementSYNOPSIS¶
snapper [--global-opts] command
[--command-opts] [ command-arguments]
snapper {--help}
DESCRIPTION¶
Snapper is a command-line program for filesystem snapshot management. It can create, delete and compare snapshots and undo changes done between snapshots. Snapper never modifies the content of snapshots. Thus snapper creates read-only snapshots if supported by the kernel. Supported filesystems are btrfs and ext4 as well as snapshots of LVM logical volumes with thin-provisioning. Some filesystems might not be supported depending on your installation.CONCEPTS¶
Configurations¶
For each filesystem or subvolume that should be snapshotted by snapper, a configuration file is required, see snapper-configs(5). The setup can be done with the create-config command.Snapshots¶
Snapper distinguishes three types of snapshots. prePre snapshots should always have a corresponding post
snapshot. The intention of pre/post snapshot pairs is to snapshot the
filesystem before and after a modification.
post
See pre type.
single
These snapshots have no special relationship to other
snapshots.
Note that filesystem-wise all three types are the same.
Snapshot Description and Userdata¶
With each snapshot a description and some userdata can be associated. The description is a string. The userdata is a list of key-value pairs where the keys and values are strings.Automatic Snapshot Creation¶
Next to manual snapshot creation, snapshots are also created automatically.•A cron-job creates hourly snapshots.
•Certain programs like YaST and zypper create
pre/post snapshot pairs when modifying the system.
Cleanup Algorithms¶
Snapper provides several algorithms to clean up old snapshots. The algorithms are executed in a daily cron-job. This can be configured in the corresponding configurations files along with parameters for every algorithm. numberDeletes old snapshots when a certain number of snapshots
is reached.
timeline
Deletes old snapshots but keeps a number of hourly,
daily, monthly and yearly snapshots.
empty-pre-post
Deletes pre/post snapshot pairs with empty diffs.
Filters¶
Some files keep state information of the system, e.g. /etc/mtab. Such files should never be reverted. To help users, snapper allows to ignore these files. Each line in all files /etc/snapper/filters/*.txt specifies a pattern. When snapper computes the difference between two snapshots it ignores all files and directories matching any of those patterns by using fnmatch(3) with the flag FNM_LEADING_DIR. Note that filters do not exclude files or directories from being snapshotted. For that, use subvolumes or mount points.GLOBAL OPTIONS¶
-q, --quietSuppress normal output. Error messages will still be
printed, though.
-v, --verbose
Increase verbosity.
--utc
Display dates and times in UTC.
--iso
Display dates and times in ISO format.
-t, --table-style
Specifies table style. Table style is identified by an
integer number.
-c, --config name
Use specified configuration instead of the default
configuration. The default configuration is named "root".
--no-dbus
Operate without a DBus connection. Only works for some
commands.
Use with caution since a running snapperd will not know about modifications made
to the system.
--version
Print version and exit.
COMMANDS¶
Snapper provides a number of commands. Each command accepts the options listed in the GLOBAL OPTIONS section. These options must be specified before the command name. In addition, many commands have specific options, which are listed in this section. These command-specific options must be specified after the name of the command and before any of the command arguments. helpShow short help text.
list-configs
List available configurations.
create-config [options] subvolume
Create a new configuration for a filesystem or subvolume.
For this command you will likely need the global option --config, see
GLOBAL OPTIONS and CONCEPTS.
-f, --fstype fstype
delete-config
Manually set filesystem type. Supported values are btrfs,
ext4 and lvm. For lvm, snapper uses LVM thin-provisioned snapshots. The
filesystem type on top of LVM must be provided in parentheses, e.g. lvm(xfs).
Without this option snapper tries to detect the filesystem.
-t, --template name
Name of template for the new configuration file.
Delete a configuration for a filesystem or subvolume. For
this command you will likely need to global option --config, see GLOBAL
OPTIONS and CONCEPTS.
get-config
Displays the settings of the configuration.
set-config configdata
Changes the settings of the configuration. The settings
configdata are a list of key-value-pairs separated by spaces and the
key and value must be separated by an equal sign, e.g.
"NUMBER_CLEANUP=yes NUMBER_LIMIT=10". The value of SUBVOLUME and
FSTYPE cannot be changed.
list (ls) [options]
List snapshots.
-t, --type type
create [options]
Selects type of snapshots to list. Possible values are
all, single and pre-post.
Create a new snapshot.
-t, --type type
modify [options] number
Specifies the type of the new snapshot. Possible values
are single, pre and post.
--pre-number number
For post snapshots the number of the pre snapshot must be
provided.
-p, --print-number
Print number of the created snapshot.
-d, --description description
Description for the snapshot.
-c, --cleanup-algorithm cleanup-algorithm
Set the cleanup algorithm for the snapshot.
-u, --userdata userdata
Set userdata for the snapshot. The key-value pairs must
be separated by comma and the key and value must be separated by an equal
sign, e.g. requestid=42,user=arthur.
--command command
Create a pre and post snapshot and run command in
between.
Modify a snapshot.
-d, --description description
delete (remove|rm) number |
number1-number2
New description for snapshot.
-c, --cleanup-algorithm cleanup-algorithm
Set the cleanup algorithm for the snapshot.
-u, --userdata userdata
Set userdata for the snapshot. The key-value pairs must
be separated by comma and the key and value must be separated by an equal
sign, e.g. requestid=42,user=arthur.
Delete a snapshot or a range of snapshots.
mount number
Mount a snapshot. Not required for all filesystem
types.
umount number
Unmount a snapshot. Not required for all filesystem
types.
status [options] number1..number2
Compare the snapshots number1 and number2.
This will show a list of files and directories that have been created,
modified or deleted in the time between the two snapshots have been made.
-o, --output file
diff [options] number1..number2
[files]
Write output to file file.
The output consists of a string encoding the status followed by the filename.
The characters of the status string are:
1.A "+" means the file was created, a
"-" means the file was deleted. A "c" means the content of
the file has changed and a "t" means the type of the file has
changed (e.g. from regular file to directory).
2.A "p" means the permissions are have
changed.
3.An "u" means the user ownership has
changed.
4.A "g" means the group ownership has
changed.
5.A "x" means the extended attribute
information has changed.
6.An "a" means the ACL information has
changed.
If there is no change a "." is outputted.Compare the snapshots number1 and number2.
This will show a diff of the content of files and directories that have been
created, modified or deleted in the time between the two snapshots have been
made.
undochange [options]
number1..number2 [files]
Undo changes done between snapshot number1 and
number2.
-i, --input file
rollback [options] [number]
Read files for which to undo changes from file
file.
Creates two new snapshots and sets the default subvolume.
Per default the system boots from the default subvolume of the root
filesystem. The exact actions depend on whether a number is provided or not:
cleanup cleanup-algorithm
•Without a number, a first read-only snapshot of
the default subvolume is created. A second read-write snapshot of the current
system is created. The system is set to boot from the second snapshot.
•With a number, a first read-only snapshot of the
current system in created. A second read-write snapshot is created of
number. The system is set to boot from the second snapshot.
Rollback is only supported with btrfs and requires a properly configured system.
-p, --print-number
Print number of the second created snapshot.
-d, --description description
Description for the snapshot.
-c, --cleanup-algorithm cleanup-algorithm
Set the cleanup algorithm for the snapshot.
-u, --userdata userdata
Set userdata for the snapshot. The key-value pairs must
be separated by comma and the key and value must be separated by an equal
sign, e.g. requestid=42,user=arthur.
Run the cleanup algorithm cleanup-algorithm.
Currently implemented cleanup algorithms are number, timeline and
empty-pre-post.
xadiff number1..number2 [files]
Compare the extended attributes between snapshot
number1 and number2. See examples below:
•+:user.foo for created attributes
•-:user.bar for removed attributes
•-+:security.selinux for modified attributes
PERMISSIONS¶
Non-root users can be allowed to use a configuration by setting ALLOW_USERS or ALLOW_GROUPS in the config file. For all operations to work, the user must also be able to read and access the .snapshots directory inside the subvolume. The .snapshots directory must be owned by root and must not be writable by anybody else. Here are some methods how to achieve that:•Make the directory accessible for everyone:
chmod a+rx .snapshots
•Make the directory accessible for a group the
user belongs to, e.g.:
chown :users .snapshots
•Make the directory accessible for the user using
ACLs, e.g.:
setfacl -m u:tux:rx .snapshots
The last method can be performed by snapper, see the SYNC_ACL setting in
snapper-configs(5).
FILES¶
/etc/sysconfig/snapperGlobal configuration file.
/etc/snapper/configs
Directory containing configuration files.
/etc/snapper/config-templates
Directory containing configuration templates.
/etc/snapper/filters/*.txt
Filter files.
/var/log/snapper.log
Logfile. Please include this file in bug reports.
NOTES¶
There is no mechanism to ensure consistency of the files while a snapshot it made. E.g. the files of a database can be inconsistent while the database is running. Consistency after undochange is not guaranteed. E.g. when the creation of a user is undone, there might still exist files from that user. Support for individual filesystems, rollback and extended attributes are compile-time options and may not be available.HOMEPAGE¶
http://snapper.io/AUTHORS¶
Arvin Schnell <aschnell@suse.de>SEE ALSO¶
snapper-configs(5), snapper-zypp-plugin(8), pam_snapper(8), btrfs(8), lvm(8), attr(5), acl(5)2014-04-07 | 0.2.4 |