snapm - Man Page

snapm is a snapshot manager for Linux systems. It manages snapshots taken at a common moment in time as a snapshot set ("snapset").

-a | --autoindex

When creating snapshot sets treat name as a common basename and generate and append a new, non-negative index value, to create a unique instance name.

This is useful when creating recurring snapshot sets of the same set of sources, for example to create a timeline of snapshots for recovery and revert purposes.

-b | --bootable

When creating snapshot sets automatically create a snapshot boot entry for the set.

-C | --calendarspec calendarspec

Calendar event expression used to trigger scheduled creation of snapshot sets. See systemd.time(7) for the expression syntax.

-c | --config schedule_name

The name of a configured schedule.

-d | --debug debug_flags

A comma-separated list of subsystem names to enable debugging output for, or 'all' to enable all debugging. The available debug classes are: manager, command, report, schedule.

-h | --help

Display usage information and exit.

--json

Produce output in JSON notation. See the JSON Output section.

--keep-count count

Retain count snapshot sets when applying the COUNT garbage collection policy.

--keep-years years

Retain years snapshot sets when applying the AGE garbage collection policy.

--keep-months months

Retain months snapshot sets when applying the AGE garbage collection policy.

--keep-weeks weeks

Retain weeks snapshot sets when applying the AGE garbage collection policy.

--keep-days days

Retain days snapshot sets when applying the AGE garbage collection policy.

--keep-yearly yearly

Retain yearly yearly snapshot sets when applying the TIMELINE garbage collection policy.

--keep-quarterly quarterly

Retain quarterly quarterly snapshot sets when applying the TIMELINE garbage collection policy.

--keep-monthly monthly

Retain monthly monthly snapshot sets when applying the TIMELINE garbage collection policy.

--keep-weekly weekly

Retain weekly weekly snapshot sets when applying the TIMELINE garbage collection policy.

--keep-daily daily

Retain daily daily snapshot sets when applying the TIMELINE garbage collection policy.

--keep-hourly hourly

Retain hourly hourly snapshot sets when applying the TIMELINE garbage collection policy.

--members

Include individual snapshots in the output of snapset show commands.

-n | --name name

Specify a snapshot set name to operate on.

--name-prefixes | --nameprefixes

Add a 'SNAPM_' prefix plus the field name to the output. Useful with --noheadings to produce a list of field=value pairs that can be used to set environment or shell variables.

--no-headings | --noheadings

Suppress output of report headings.

-o | --options fields

Specify which fields to display.

-O | --sort sort_fields

Specify which fields to sort by.

-p | --policy-type policy_type

Select the garbage collection policy applied to snapshot sets created by a schedule. Valid values are ALL, COUNT, AGE, and TIMELINE.

-r | --revert

When creating snapshot sets automatically create a snapshot revert entry for the set.

--rows

Output report columns as rows.

--separator separator

Report field separator.

-s | --size-policy size_policy

Specify a default size policy when creating snapshot sets.

-N | --snapshot-name name

Specify a snapshot name to operate on.

-U | --snapshot-uuid UUID

Specify a snapshot UUID to operate on.

--start

Start the specified schedule immediately when enabling it with snapm schedule enable.

-u | --uuid UUID

Specify a snapshot set UUID to operate on.

-v | --verbose

Increase verbosity level. Specify multiple times, or set additional debug classes with --debug to enable more verbose messages.

-V | --version

Display the version of snapm and exit.

The snapm command manages named collections of snapshots taken at a common point in time as snapshot sets. A snapshot set is created from a list of sources (mount point or block device paths) and allows the state of the system to be captured spanning over several volumes.

Valid characters for snapshot set names are: a–z A–Z 0–9 + . -

The underscore character ('_') is not permitted.

Snapshot sets and snapshots are also identified by a unique UUID value.

A plugin model is used to map mount points or devices onto possible snapshot providers. A provider plugin must exist for each source path specified when creating a snapshot set. The current plugins support LVM2 copy-on-write, LVM2 thin provisioned and Stratis snapshots.

The snapset subcommand allows snapshot sets to be created, deleted, enumerated, renamed, reverted, and activated or deactivated.

The snapshot subcommand provides access to information describing individual snapshots that are part of a snapshot set, for example the device path and snapshot status.

Snapshot manager commands consist of a type (snapset, snapshot, plugin, schedule), followed by a type-specific subcommand.

Snapshot Set Commands

snapm

snapset create [-b|--bootable] [-r|--revert] [-s|--size-policy policy] [-a|--autoindex] [--json] name source[size_policy]...
Create a new snapshot set using the specified list of mount points and block devices.

The newly created snapshot set is displayed on the terminal on success:

    # snapm snapset create backup / /home /var /opt /srv
    SnapsetName:      backup
    Sources:          /, /home, /var, /opt, /srv
    NrSnapshots:      5
    Time:             2024-12-05 17:46:12
    UUID:             87c89914-51a5-5043-8513-667100213243
    Status:           Inactive
    Autoactivate:     no
    Bootable:         no

When creating snapshot sets --bootable and --revert can optionally be used to automatically create snapshot boot and revert boot entries respectively.

A size policy can be specified on the create command line, either as a global default or individually for each source path. To specify a default policy use the --size-policy argument.  To specify a per-source path size policy append the policy to the source path separated by the : character:

# snapm snapset create backup --size-policy 25%FREE /:4G /home /var
SnapsetName:      backup
Sources:          /, /home, /var
NrSnapshots:      3
Time:             2024-12-05 17:47:19
UUID:             4106d5b5-b521-504d-8822-8826594debb5
Status:           Inactive
Autoactivate:     no
Bootable:         no

Snapshot providers that do not allocate a fixed size for snapshot data will check for available space according to the policy at creation time but do not enforce a fixed size for individual snapshots: space is allocated from the available pool on an as-needed basis.

If the --autoindex argument is given the name given on the command line is treated as a basename and a new, non-negative integer index will be generated and appended to the name to construct a new, unique instance name. This can be used to group a series of snapshot sets of the same set of sources that are taken on a recurring schedule.

    # snapm snapset create hourly --autoindex /:5%SIZE /var:5%SIZE
    SnapsetName:      hourly.3
    Sources:          /, /var
    NrSnapshots:      2
    Time:             2025-03-26 14:17:18
    UUID:             ae082452-7995-5316-ac65-388eadd9879c
    Status:           Active
    Autoactivate:     yes
    Bootable:         no

snapm

snapset create-scheduled -c|--config schedule_name [--json]
Create scheduled snapshot sets according to named configuration. This command is normally called by the corresponding schedule timer. It may be issued manually for testing or debugging purposes, or to create additional snapshot sets not specified by the schedule parameters.

snapm

snapset delete [name|UUID] [-n|--name name] [-u|--uuid UUID]
Delete the specified snapshot set. The snapshot set to delete may be specified either by its name or UUID.

snapm

snapset rename old_name new_name
Rename an existing snapshot set. The snapshot set to be renamed is specified as old_name and the new name is given as new_name.

snapm

snapset revert [name|UUID] [-n|--name name] [-u|--uuid UUID]
Revert an existing snapshot set, re-setting the content of the origin volumes to the state they were in at the time the snapshot set was created. The snapshot set to be reverted may be specified either by its name or UUID.

Reverting a snapshot set with mounted and in-use origin volumes will schedule the revert to take place the next time that the volumes are activated, for example by booting into a configured revert boot entry for the snapshot set.

snapm

snapset resize [name|UUID] [-n|--name name] [-u|--uuid UUID] [-s|--size-policy policy] [source[size_policy]...]
Resize the members of an existing snapshot set, re-applying size policies to one or more of the snapshots making up the set. The snapshot set to resize may be specified by either its name or UUID.

For snapshot providers that require a fixed space to be allocated to the snapshot this command will physically resize the corresponding snapshot according to the given size policy (lvm2-cow). For snapshot providers that dynamically allocate space the command will check that the requested space is available at the time of the resize command. An error is returned if the specified size policies cannot be satisfied.

Size policies may be specified on a per-source basis using the same syntax as the snapset create command. A default size policy can be set using the --size-policy argument. If no source paths are specified the command applies the default size policy to each member of the snapshot set.

The lvm2-cow plugin does not support shrinking snapshots, as this is not supported by the LVM2 tools.

snapm

snapset split name new_name source...
Split snapshots from an existing snapshot set into a new snapshot set.

Split the snapshot set named name into a new snapshot set named 'new_name'. Each listed source from 'name' is split into the new snapshot set. Sources that are not listed on the command line remain part of the original snapshot set. It is an error to split all sources from a snapshot set: in this case use 'snapm snapset rename' instead.

snapm

snapset prune name source...
Prune snapshots from an existing snapshot set.

Prune the listed sources from the snapshot set named name. The listed snapshot sources are pruned from the snapshot set and permanently deleted. This operation is irreversible.

It is an error to prune all sources from a snapshot set: in this case use 'snapm snapset delete' instead.

snapm

snapset activate [name|UUID] [-n|--name name] [-u|--uuid UUID]
Attempt to activate snapshots making up snapshot sets. If no argument is given the command will attempt to activate all snapshots of all snapshot sets present on the system. If a name or UUID is specified then only that snapshot set will be activated.

Not all snapshot providers support optional activation for snapshot volumes: for these providers activate and deactivate have no effect on volume availability.

snapm

snapset deactivate [name|UUID] [-n|--name name] [-u|--uuid UUID]
Attempt to deactivate snapshots making up snapshot sets. If no argument is given the command will attempt to deactivate all snapshots of all snapshot sets present on the system. If a name or UUID is specified then only that snapshot set will be deactivated.

Not all snapshot providers support optional activation for snapshot volumes: for these providers activate and deactivate have no effect on volume availability.

snapm

snapset autoactivate --yes|--no [name|UUID] [-n|--name name] [-u|--uuid UUID]
Enable or disable snapshot autoactivation for snapshot sets matching selection criteria. Some snapshot providers (lvm2-thin) support optional snapshot volume activation when activating resources for e.g. at boot time. The snapset autoactivate subcommand allows control of this behaviour for snapshot sets managed by snapm.

snapm

snapset list [name|UUID] [-n|--name name] [-u|--uuid UUID] [--name-prefixes|--nameprefixes] [--no-headings|--noheadings] [-o|--options fields] [-O|--sort sort_fields] [--rows|--json] [--separator separator]
Output a tabular report of snapshot sets.

Displays a report with one snapshot set per line, containing fields describing the properties of the configured snapshot sets.

The list of fields to display is given with -o|--options as a comma separated list of field names. To obtain a list of available fields run 'snapm snapset list -o help'. If the list of fields begins with the '+' character the specified fields are appended to the default field list. Otherwise the given list of fields replaces the default set of report fields.

The --rows, --noheadings, and --nameprefixes options can be used to generate output in a machine readable form, suitable for setting shell or environment variables.

Report output may be sorted by multiple user-defined keys using the --sort option. The option expects a comma separated list of keys, with optional + and - prefixes indicating ascending and descending sort for that field respectively.

snapm

snapset show [name|UUID] [-n|--name name] [-u|--uuid UUID] [--members] [--json]
Display snapshot sets matching selection criteria on standard out. If the --members option is given individual snapshots are included in the output.

Snapshot Commands

snapm

snapshot activate [name|UUID] [-n|--name name] [-u|--uuid UUID] [-N|--snapshot-name name] [-U|--snapshot-uuid UUID]
Attempt to activate individual snapshots matching selection criteria. If no argument is given the command will attempt to activate all snapshots of all snapshot sets present on the system. If a snapshot or snapshot set name or UUID is specified then only matching volumes will be activated.

Not all snapshot providers support optional activation for snapshot volumes: for these providers activate and deactivate have no effect on volume availability.

snapm

snapshot deactivate [name|UUID] [-n|--name name] [-u|--uuid UUID] [-N|--snapshot-name name] [-U|--snapshot-uuid UUID]
Attempt to deactivate individual snapshots matching selection criteria. If no argument is given the command will attempt to deactivate all snapshots of all snapshot sets present on the system. If a snapshot or snapshot set name or UUID is specified then only matching volumes will be deactivated.

Not all snapshot providers support optional activation for snapshot volumes: for these providers activate and deactivate have no effect on volume availability.

snapm

snapshot autoactivate --yes|--no [name|UUID] [-n|--name name] [-u|--uuid UUID] [-N|--snapshot-name name] [-U|--snapshot-uuid UUID]
Enable or disable snapshot autoactivation for individual snapshots matching selection criteria. Some snapshot providers (lvm2-thin) support optional snapshot volume activation when activating resources for e.g. at boot time. The snapshot autoactivate subcommand allows control of this behaviour for individual snapshots managed by snapm.

snapm

snapshot list [name|UUID] [-n|--name name] [-u|--uuid UUID] [-N|--snapshot-name name] [-U|--snapshot-uuid UUID] [--name-prefixes|--nameprefixes] [--no-headings|--noheadings] [-o|--options fields] [-O|--sort sort_fields] [--rows|--json] [--separator separator]
Output a tabular report of snapshots.

Displays a report with one snapshot per line, containing fields describing the properties of the configured snapshots.

The list of fields to display is given with --options as a comma separated list of field names. To obtain a list of available fields run 'snapm snapshot list -o help'. If the list of fields begins with the '+' character the specified fields are appended to the default field list. Otherwise the given list of fields replaces the default set of report fields.

The --rows, --noheadings, and --nameprefixes options can be used to generate output in a machine readable form, suitable for setting shell or environment variables.

Report output may be sorted by multiple user-defined keys using the --sort option. The option expects a comma separated list of keys, with optional + and - prefixes indicating ascending and descending sort for that field respectively.

snapm

snapshot show [name|UUID] [-n|--name name] [-u|--uuid UUID] [-N|--snapshot-name name] [-U|--snapshot-uuid UUID] [--json]
Display snapshots matching selection criteria on standard out.

Plugin Commands

snapm

plugin list [--name-prefixes|--nameprefixes] [--no-headings|--noheadings] [-o|--options fields] [-O|--sort sort_fields] [--rows|--json] [--separator separator]
Output a tabular report of plugins.

Displays a report with one plugin per line, containing fields describing the properties of the available plugins.

The list of fields to display is given with --options as a comma separated list of field names. To obtain a list of available fields run 'snapm plugin list -o help'. If the list of fields begins with the '+' character the specified fields are appended to the default field list. Otherwise the given list of fields replaces the default set of report fields.

The --rows, --noheadings, and --nameprefixes options can be used to generate output in a machine readable form, suitable for setting shell or environment variables.

Report output may be sorted by multiple user-defined keys using the --sort option. The option expects a comma separated list of keys, with optional + and - prefixes indicating ascending and descending sort for that field respectively.

Schedule Commands

snapm

schedule create -p|--policy-type policy_type [-b|--bootable] [-C|--calendarspec calendarspec] [-r|--revert] [-s|--size-policy policy] [--keep-count count] [--keep-years years] [--keep-months months] [--keep-weeks weeks] [--keep-days days] [--keep-yearly yearly] [--keep-quarterly quarterly] [--keep-monthly monthly] [--keep-weekly weekly] [--keep-daily daily] [--keep-hourly hourly] schedule_name source[size_policy]...
Create a new snapshot set schedule.

Create a persistent schedule to automatically create snapshot sets according to the name and arguments given to the snapm schedule create command.

Scheduled snapshot sets are created with the autoindex argument enabled, to ensure uniqueness of the created snapshot set names.

New snapshot sets will be automatically created as configured by the specified calendar event expression (--calendarspec).

The snapm schedule create command accepts the same set of arguments as the snapm snapset create command (with the exception of --autoindex, which is always enabled for scheduled snapshot set creation) and these are passed on to the snapshot sets created by the schedule.

A garbage collection policy specified by the --policy-type and configured by the corresponding --keep-* arguments is applied to automatically delete snapshot sets that are no longer required.

Newly created schedules are automatically enabled and will begin creating snapshot sets at the first expiry of the configured calendar expression.

    # snapm schedule create --policy-type count --keep-count 2 --bootable --revert --size-policy 25%SIZE --calendarspec hourly hourly / /var
    Name: hourly
    Sources: /, /var
    DefaultSizePolicy: 25%SIZE
    Calendarspec: hourly
    Boot: yes
    Revert: yes
    GcPolicy:
        Name: hourly
        Type: Count
        Params: keep_count=2
    Enabled: yes
    Running: yes
    NextElapse: 2025-08-23 04:00:00

snapm

schedule delete schedule_name
Delete snapshot set schedule.

Delete an existing snapshot set schedule by name. The specified schedule is disabled and removed from the system. Existing snapshot sets created by the schedule before its deletion remain and continue to be available until deleted by the user.

snapm

schedule edit [-p|--policy-type policy_type] [-b|--bootable] [-C|--calendarspec calendarspec] [-r|--revert] [-s|--size-policy policy] [--keep-count count] [--keep-years years] [--keep-months months] [--keep-weeks weeks] [--keep-days days] [--keep-yearly yearly] [--keep-quarterly quarterly] [--keep-monthly monthly] [--keep-weekly weekly] [--keep-daily daily] [--keep-hourly hourly] schedule_name [source[size_policy]...]
Modify an existing snapshot set schedule.

Modify a persistent schedule to automatically create snapshot sets according to the name and arguments given to the snapm schedule edit command. Arguments not specified on the edit command line are taken from the existing schedule.

The snapm schedule edit command accepts the same set of arguments as the snapm schedule create command.

If -p policy_type is provided without type-specific parameters, the existing policy is retained (except for the all policy type, which has no parameters and is applied directly).

snapm

schedule enable schedule_name [--start]
Enable existing snapshot set schedule.

Enable an existing snapshot set schedule by name. The specified schedule is enabled and will be started on subsequent reboots. To start the schedule timer immediately use --start.

snapm

schedule disable schedule_name
Disable existing snapshot set schedule.

Disable an existing snapshot set schedule by name. The specified schedule is stopped and disabled, and will no longer automatically start on subsequent reboots.

snapm

schedule list [--name-prefixes|--nameprefixes] [--no-headings|--noheadings] [-o|--options fields] [-O|--sort sort_fields] [--rows|--json] [--separator separator]
Output a tabular report of configured schedules.

Displays a report with one schedule per line, containing fields describing the properties of the configured schedules.

The list of fields to display is given with -o|--options as a comma separated list of field names. To obtain a list of available fields run 'snapm schedule list -o help'. If the list of fields begins with the '+' character the specified fields are appended to the default field list. Otherwise the given list of fields replaces the default set of report fields.

The --rows, --noheadings, and --nameprefixes options can be used to generate output in a machine readable form, suitable for setting shell or environment variables.

Report output may be sorted by multiple user-defined keys using the --sort option. The option expects a comma separated list of keys, with optional + and - prefixes indicating ascending and descending sort for that field respectively.

    # snapm schedule list
    ScheduleName ScheduleSources SizePolicy OnCalendar Enabled NextElapse
    daily        /, /var         10%SIZE    daily      yes     2025-08-25 00:00:00

snapm

schedule gc -c|--config schedule_name
Run garbage collection for snapshot set schedule.

Run the configured garbage collection policy for the schedule specified with -c | --config schedule_name.
Cleans up snapshot sets created by schedule_name, applying the configured cleanup policy and parameters given to snapm schedule create.

The names of deleted snapshot sets are printed to standard output.

Snapshot manager supports automatically creating snapshot sets according to a user-defined schedule. A garbage collection policy provides for automatically cleaning up snapshot sets that are no longer required according to a user defined policy and retention parameters.

Snapshot set schedules are created with the snapm schedule create command. The command accepts the same set of arguments as snapm snapset create allowing the properties of scheduled snapshot sets to be controlled by the user.

Garbage collection policies

ALL

Retain all snapshot sets. This policy accepts no parameters and never deletes snapshot sets automatically.

COUNT

Retain a fixed number of snapshot sets. This policy accepts a single parameter, --keep-count=count and retains up to count snapshot sets.

AGE

Retain snapshot sets younger than specified age. This policy accepts up to four parameters (--keep-years=years, --keep-months=months, --keep-weeks=weeks, --keep-days=days) and retains snapshot sets that were created more recently than the specified age limit. The limit applied is the sum of the parameters given.

TIMELINE

Retain snapshot sets according to classification. Each snapshot set is classified as hourly, daily, weekly, monthly, quarterly, or yearly according to its creation time: the first snapshot set taken at the beginning of each hour is classified as hourly, the first taken after midnight each day as daily, the first taken after midnight each Monday as weekly, and so on. A fixed number of snapshot sets is retained for each classification according to the value of the --keep-hourly, --keep-daily, --keep-monthly, --keep-quarterly, and --keep-yearly parameters.

Snapshot manager integrates with the boom(8) boot manager to facilitate booting and reverting snapshot sets. Specifying the -b|--bootable or -r|--revert arguments when creating a snapshot set will cause snapm to create a snapshot boot or revert boot entry respectively.

The snapshot boot entry allows the system to boot into the state of the system at the time the snapshot was created. This can be used to inspect the previous state of the system or to quickly recover from a failed update or reconfiguration.

In order to reset the system back to the state at the time the snapshot set was created the revert boot entry is used after issuing a snapm snapset revert command. After running the revert command the system should be rebooted into the revert boot entry. This will start the revert operation on all affected volumes.

While the operation is in progress the snapshot set will appear with the status of Reverting.

Reverting a snapshot set will also destroy the snapshot set since the snapshot volumes are folded back into the origin devices. Following the completion of a revert operation the snapshot set will no longer appear in the output of snapm snapset list or snapm snapset show commands.

Both the snapset list and snapshot list commands use a common reporting system to display the results of the query. The selection of fields, and the order in which they are displayed may be controlled to produce custom report formats using the -o/--options argument. The report output can also be optionally sorted by one or more field values using the -O/--sort argument.

To display the available fields for a given report type use the special field name help:

    # snapm snapset list -o help
    Snapshot set Fields
    -------------------
      name         - Snapshot set name [str]
      UUID         - Snapshot set UUID [UUID]
      basename     - Snapshot set basename [str]
      index        - Snapshot set index [idx]
      timestamp    - Snapshot set creation time as a UNIX epoch value [num]
      time         - Snapshot set creation time [time]
      nr_snapshots - Number of snapshots [num]
      sources      - Snapshot set sources [strlist]
      mountpoints  - Snapshot set mount points [strlist]
      devices      - Snapshot set devices [strlist]
      status       - Snapshot set status [str]
      autoactivate - Autoactivation status [str]
      bootable     - Configured for snapshot boot [str]
      bootentry    - Snapshot set boot entry [sha]
      revertentry  - Snapshot set revert boot entry [sha]

The snapm reports provide several types of field that may be added to the default field set for either snapshot set or snapshot reports, or used to create custom reports.

All reporting commands can optionally generate output in JSON notation by using the --json argument. The output is a JSON object containing a key for the object type (Snapsets, Snapshots, Plugins, or Schedules) that contains a JSON array of objects of the specified type.

Reporting commands use JSON key names derived from the report field names. For list reports the JSON keys are always prefixed with the object type to avoid collisions (e.g., snapset_name). The -o/--options and -O/--sort arguments accept those report field names (prefixes are optional unless required to disambiguate).

Selection and sorting is controlled with --options and --sort as usual:

    # snapm snapset list --json -o+snapset_uuid --sort snapset_time
    {
        "Snapsets": [
            {
                "snapset_name": "before-upgrade",
                "snapset_time": "2025-09-08 18:43:57",
                "snapset_nr_snapshots": 2,
                "snapset_status": "Active",
                "snapset_sources": [
                    "/",
                    "/var"
                ],
                "snapset_uuid": "6330328b-a9d0-5b41-ac96-53b371449965"
            },
            {
                "snapset_name": "backup",
                "snapset_time": "2025-09-09 17:12:21",
                "snapset_nr_snapshots": 3,
                "snapset_status": "Inactive",
                "snapset_sources": [
                    "/",
                    "/home",
                    "/var"
                ],
                "snapset_uuid": "efa8a09d-cf9c-500b-ad68-32c4a0e159b4"
            }
        ]
    }

The create, create-scheduled, and show subcommands also support optional JSON notation using the --json argument. This includes the snapset, snapshot, and schedule show subcommands:

    # snapm snapset show --json before-upgrade
    [
        {
            "SnapsetName": "before-upgrade",
            "Sources": [
                "/",
                "/home",
                "/var"
           ],
            "MountPoints": [
                "/",
                "/home",
                "/var"
            ],
            "Devices": [],
            "NrSnapshots": 3,
            "Timestamp": 1755915019,
            "Time": "2025-08-23 03:10:19",
            "UUID": "d9b63a58-333b-517a-b38d-7cc818040fab",
            "Status": "Active",
            "Autoactivate": true,
            "Bootable": true,
            "BootEntries": {
                "SnapshotEntry": "61cb664",
                "RevertEntry": "74c1cf2"
            }
        }
    ]

The JSON format produced by the create and show commands uses JSON key names that reflect the property names used in the normal show command output. The output is a JSON array containing objects of the specified type.

When boot entries are defined for a snapshot set the resulting JSON will include a BootEntries object giving the corresponding boom boot_id values.

The create commands output a single JSON object of the corresponding type. The show commands produce a JSON array containing the selected objects.

List the available snapshot sets

    # snapm snapset list
    SnapsetName  Time                 NrSnapshots Status   Sources
    backup       2024-12-05 17:53:10            4 Active   /, /opt, /srv, /var
    userdata     2024-12-05 17:53:22            2 Inactive /data, /home

List the available snapshots

    # snapm snapshot list
    SnapsetName  Name                                          Origin              Source  Status   Size     Free     Autoactivate Provider
    backup       fedora/root-snapset_backup_1733421190_-       /dev/fedora/root    /       Active     8.8GiB   8.8GiB yes          lvm2-cow
    backup       fedora/var-snapset_backup_1733421190_-var     /dev/fedora/var     /var    Active     6.4GiB   6.4GiB yes          lvm2-cow
    backup       p1/fs2-snapset_backup_1733421190_-srv         /dev/stratis/p1/fs2 /srv    Active     2.0GiB   3.2GiB yes          stratis
    backup       p1/fs1-snapset_backup_1733421190_-opt         /dev/stratis/p1/fs1 /opt    Active     1.0GiB   3.2GiB yes          stratis

List the available snapshots, displaying the basename and index for each

    # snapm snapset list -o+basename,index
    SnapsetName  Time                 NrSnapshots Status  Sources  Basename     Index
    backup       2025-03-25 18:12:54            2 Invalid /, /var  backup           -
    hourly.0     2025-03-26 14:00:00            2 Invalid /, /var  hourly           0
    hourly.1     2025-03-26 15:00:00            2 Active  /, /var  hourly           1
    hourly.2     2025-03-26 16:00:00            2 Active  /, /var  hourly           2
    hourly.3     2025-03-26 17:00:00            2 Active  /, /var  hourly           3

Create a new snapshot set from the mount points /, /home, and /var

    # snapm snapset create backup / /home /var
    SnapsetName:      backup
    Sources:          /, /home, /var
    NrSnapshots:      3
    Time:             2024-12-05 17:57:05
    UUID:             b9b4cd96-75a5-5826-a26b-b617c06bd877
    Status:           Active
    Autoactivate:     no
    Bootable:         no

Create a bootable snapshot set from the mount points /, /home, and /var

    # snapm snapset create -br before-upgrade / /home /var
    SnapsetName:      before-upgrade
    Sources:          /, /home, /var
    NrSnapshots:      3
    Time:             2025-08-23 03:10:19
    UUID:             d9b63a58-333b-517a-b38d-7cc818040fab
    Status:           Active
    Autoactivate:     yes
    Bootable:         yes
    BootEntries:
      SnapshotEntry:  61cb664
      RevertEntry:    74c1cf2

Create a bootable snapshot set from the mount points /, /home, and /var, with output formatted in JSON notation

    # snapm snapset create -br --json before-upgrade / /home /var
    {
        "SnapsetName": "before-upgrade",
        "Sources": [
            "/",
            "/home",
            "/var"
        ],
        "MountPoints": [
            "/",
            "/home",
            "/var"
        ],
        "Devices": [],
        "NrSnapshots": 3,
        "Timestamp": 1755915019,
        "Time": "2025-08-23 03:10:19",
        "UUID": "d9b63a58-333b-517a-b38d-7cc818040fab",
        "Status": "Active",
        "Autoactivate": true,
        "Bootable": true,
        "BootEntries": {
            "SnapshotEntry": "61cb664",
            "RevertEntry": "74c1cf2"
        }
    }

Delete the snapshot set named 'backup'

    # snapm snapset delete backup

Activate all snapshot sets with verbose output

    # snapm -v snapset activate
    INFO - Activated 2 snapshot sets

Rename the snapshot set 'backup' to 'oldbackup'

    # snapm snapset rename backup oldbackup

Display the snapshot set named 'before-upgrade'

    # snapm snapset show before-upgrade
    SnapsetName:      before-upgrade
    Sources:          /, /home, /var
    NrSnapshots:      3
    Time:             2025-08-23 03:10:19
    UUID:             d9b63a58-333b-517a-b38d-7cc818040fab
    Status:           Active
    Autoactivate:     yes
    Bootable:         yes
    BootEntries:
      SnapshotEntry:  61cb664
      RevertEntry:    74c1cf2

Display the snapshot with UUID b201bdba-89b7-5014-a80d-f5d4b9a690ed

    # snapm snapshot show -U b201bdba-89b7-5014-a80d-f5d4b9a690ed
    Name:           fedora/home-snapset_before-upgrade_1755915019_-home
    SnapsetName:    before-upgrade
    Origin:         /dev/fedora/home
    Time:           2025-08-23 03:10:19
    Source:         /home
    MountPoint:     /home
    Provider:       lvm2-thin
    UUID:           b201bdba-89b7-5014-a80d-f5d4b9a690ed
    Status:         Active
    Size:           1.0GiB
    Free:           1.9GiB
    Autoactivate:   yes
    DevicePath:     /dev/fedora/home-snapset_before-upgrade_1755915019_-home
    VolumeGroup:    fedora
    LogicalVolume:  home-snapset_before-upgrade_1755915019_-home

snapm exits with one of the following status codes:

0

Command completed successfully.

1

A runtime error occurred.

2

Invalid arguments or option parsing error.

Configuration is read from the following locations:

/etc/snapm/snapm.conf
/etc/snapm/plugins.d
/etc/snapm/schedule.d

The main configuration file is /etc/snapm/snapm.conf. Plugin-specific settings are stored in plugins.d, and snapshot schedules are defined in schedule.d.

Please report bugs via the GitHub issue tracker:

⟨https://github.com/snapshotmanager/snapm/issues⟩

Bryn M. Reeves <bmr@redhat.com>

snapm.conf(5). snapm-plugins.d(5). snapm-schedule.d(5). systemd.time(7). boom(8). lvm(8). stratis(8).
⟨https://github.com/snapshotmanager/snapm⟩ snapm project page

⟨https://github.com/snapshotmanager/boom⟩ Boom project page

⟨https://www.sourceware.org/lvm2/⟩ LVM2 resource page

⟨https://stratis-storage.github.io/⟩ Stratis resource page

snapm-schedule.d(5).