Quickstart guide
A snap is a bundle of one or more applications that works without modification across many different Linux distributions. Snaps are discoverable and installable from the Snap Store, a public app store with an audience of millions.
This tutorial introduces all of snap’s main features. We suggest going through the first few steps and then playing with what you’ve learnt. Come back when you feel comfortable and wish to further your knowledge.
By the end of this tutorial, you’ll have a good understanding of how to use snaps, from how they’re installed and updated, to how they’re backed-up and removed.
Requirements
This tutorial is suitable for users of any system that supports snaps, but we use Ubuntu for our examples.
Snaps can be installed and removed via a graphical package manager, such as Ubuntu Software Centre, but most advanced functionality is only available from the Linux command line. It helps if you have some familiarity with this, but if you don’t, this tutorial is itself an ideal introduction to get you started.
All the following commands are run from the Terminal application.
Find a snap
There are snaps for many popular applications, including Spotify, Slack and the Chromium web browser.
The best way to find new snaps is to use the online Snap Store, either by searching for apps and words you’re interested in, such as “Spotify”, “music” or “maths”, or by browsing through categories.
The snap command is used locally to access and manage all of snap’s packaging features. Typing snap on its own will display the brief help text and list of example commands, including the find command which is used to search for snaps.
To search for snaps with ‘media player’ in either their names or descriptions, type snap find "media player" into your terminal:
$ snap find "media player"
Name Version Developer Notes Summary
(...)
vlc 3.0.4 videolan✓ - The ultimate media player.
mpv 0.26.0 casept - a free, open source, and cross-platform media player.
(...)
The ✓ alongside videolan in the above output indicates that the snap publisher has been verified.
The find output can be limited to snaps from specific categories, such as music-and-audio, with an additional --section= argument:
$ snap find "media player" --section="featured"
Name Version Publisher Notes Summary
foobar2000 1.6.12 mmtrt - foobar2000 is an advanced freeware audio player.
vlc 3.0.16 videolan✓ - The ultimate media player
Snap categories
Typing snap find without any arguments will return a list of suggested snaps and those suggestions can also be filtered to a category with the same --section= argument. The following section names are valid:
| art-and-design | books-and-reference | development | devices-and-iot |
| education | entertainment | featured | finance |
| games | health-and-fitness | music-and-audio | news-and-weather |
| personalisation | photo-and-video | productivity | science |
| security | server-and-cloud | social | utilities |
Learn about a snap
The snap info command makes it easy to find more details about a specific snap. These details include what a snap does, who publishes it, which commands it provides.
Typing snap info vlc, for example, will produce output similar to the following:
name: vlc
summary: The ultimate media player
publisher: VideoLAN✓
contact: https://www.videolan.org/support/
description: |
VLC is the VideoLAN project's media player.
---
snap-id: RT9mcUhVsRYrDLG8qnvGiy26NKvv6Qkd
commands:
- vlc
channels:
latest/stable: 3.0.16 2021-06-28 (2344) 310MB -
latest/candidate: 3.0.16 2021-06-28 (2344) 310MB -
latest/beta: 3.0.18-rc-38-gcc4c37ebb3 2022-09-20 (3021) 335MB -
latest/edge: 4.0.0-dev-20763-g15bf12a0f3 2022-09-20 (3022) 659MB -
Add the --verbose option to info to retrieve more details, including expanded notes and details on which base the snap uses.
The final part of the output lists the channels for the snap. Channels declare which release of a snap is installed and tracked for updates. The latest/stable channel is used by default, but opting to install from a different channel can be useful for testing new features, or for installing old legacy versions of an application. Which snaps are released to which channels is entirely up to the snap publisher.
Install the snap
Type snap install followed by the name of the snap to install the snap:
sudo snap install vlc
A channel can be optionally specified with the channel option:
sudo snap install --channel=edge vlc
After installation, the channel being tracked can be changed with:
sudo snap switch --channel=stable vlc
The sudo command ensures the command following it is executed as the root administrative user.
While not a requirement for using snaps, creating an Ubuntu One/SSO account, and authenticating once with snap login <email-address>, removes the need to use sudo with snap commands.
Run apps and commands from the snap
A snap’s installed applications can be found under /snap/bin, and subsequently, often are to the system $PATH. This makes snapped applications and commands directly accessible from the desktop and from the command line.
For example, the command installed via the VLC snap is vlc:
$ which vlc
/snap/bin/vlc
If executing a command directly doesn’t work, use the snap run command:
snap run vlc
Connect an interface
Interfaces permit or deny access to a resource outside a snap’s confinement.
They’re most commonly used to enable access to a webcam, to permit sound recording, for network access, or to read and write to your $HOME directory.
Which interfaces a snap requires, and provides, is very much dependent on the type of snap and its own requirements.
To see which interfaces a snap is using, and which interfaces it could use but isn’t, type snap connections <snapname>:
$ snap connections vlc
Interface Plug Slot Notes
audio-playback vlc:audio-playback :audio-playback -
audio-record vlc:audio-record - -
camera vlc:camera - -
desktop vlc:desktop :desktop -
home vlc:home :home -
(...)
The slot is the provider of the resource while the plug is the consumer, and a slot can support multiple plug connections. In the above output, the camera interface is not connected because its slot is empty. This means VLC cannot access any connected cameras. The <snap-name>:<interface-name> syntax describes which snap is responsible for which component. If there’s no snap, such as with :audio-playback, the component is directly connected to the system.
To allow a camera to be accessible to VLC, the interface can be connected with the snap connect command:
snap connect vlc:camera
The Ubuntu Software/Snap Store desktop application can also be used to enable and disable interface connections.
To access its interface management functions, either search for an installed snap, or select it from the Manage view. The interfaces for the selected application can then be viewed by selecting Permissions :
As you can see the output from snap connections vlc, and in the above image, VLC already has access a user’s /home directory because the home interface is connected to the system $HOME directory. This is an automatic connection, and is granted to certain interfaces and snaps when an interface provides fundamental functionality, such as VLC accessing your personal video and audio files.
Refer to Interfaces for more information.
Where snaps store data
Most snaps use strict confinement. This isolates both their execution environments and their data from your system (see Snap Confinement for further details). A confined snap that needs user-access to files will most likely use the home interface to bridge this confinement gap, allowing you to save and load files from your home directory automatically.
You can see whether the home interface is being used in the output to snap connections <snap name>:
$ snap connections nethack
Interface Plug Slot Notes
home nethack:home :home -
Regardless of whether the home interface is used or not, a snap can also store user data, such as a database or configuration files, within its own directory under $HOME/snap. Data within this snap-specific directory is stored in one of two further directories, depending on whether the data needs to be tied to a specific release, or whether it can be used across multiple releases.
Data for a specific release is stored within a directory named after the revision of a release. This is a numeric value, such as 55 or 56. The data for each specific revision is often copied from one release to the next, so that reverting from one revision to a previous revision will restore a working configuration, for instance. The snap directory also contains a symbolic link called current that points to the snap revision currently active.
Data that can be shared across releases is stored in a directory called common, and might include image or audio caches, or a database. This data is not copied between releases.
For more details on where snaps store their data, see Data locations.
List installed snaps
Use snap list to show a list of snaps installed on your system:
$ snap list
Name Version Rev Tracking Publisher Notes
core 16-2.35.1 5419 beta canonical✓ core
spotify 1.0.88.353 19 stable spotify✓ -
vlc 3.0.4 555 stable videolan✓ -
Some snaps, such as core listed above, are installed automatically by snapd to satisfy the requirements of other snaps.
Update an installed snap
Snaps are updated automatically. However, to manually check for updates, use the following command:
sudo snap refresh vlc
The above will check the channel being tracked by the snap. If a newer version of the snap is available, it will be downloaded and installed.
Changing the channel being tracked and refreshing the snap can be accomplished with a single command:
sudo snap refresh --channel=beta vlc
Updates are automatically installed within 6 hours of a revision being made to a tracked channel, keeping most systems up-to-date. This schedule can be tuned via configuration options.
Refer to Managing updates for more details.
Pause or stop automatic updates
The snap refresh --hold command holds, or postpones, snap updates for individual snaps, or for all snaps on the system, either indefinitely or for a specified period of time.
snap refresh --hold=<duration> <snap1> <snap2>...
Time duration units can be seconds (s), minutes (m) or hours (h), or a combination of these. To postpone updates indefinitely, a value of forever is also valid.
$ snap refresh --hold=24h firefox
General refreshes of "firefox" held until 2023-10-26T14:10:53+01:00
If no duration is specified, the time duration defaults to forever.
Versions and revisions
Versions and revisions convey different details about one specific release of a snap:
- Version : the version of the software being packaged, as assigned by the developers
- Revision: the sequence number assigned by the store when the snap file was uploaded
The version is a string that was assigned to a project by its developers, according to their development practices. It tells the user what content to expect from a snap. The revision is an automatic number assigned by the Snap store, giving the snap a unique identity within the channel.
Neither the version nor the revision enforce an order of release. The local system will simply attempt to install whatever snap is recommended by the publisher in the channel being tracked.
Revert to an earlier revision
A snap may be reverted to an earlier revision with the snap revert command. By default, it will attempt to revert to the previous revision:
$ sudo snap revert vlc
vlc reverted to 3.0.5-1
The optional --revision argument can be specified to request a specific revision:
snap revert vlc --revision 500
This operation will revert both the snap revision and the configuration data associated with the software. If the previously used revision of the snap is from a different channel, that snap will be installed but the channel being tracked won’t change.
User data, such as data generated by the snap and stored in a database, is often stored in a common directory and will not be reverted. See Data locations for more details on what information is stored and where.
A snap won’t automatically update to a version previously reverted from, and the output from snap refresh will continue to state All snaps up to date. A reverted snap will be automatically updated when a new and different revision is made available by the publisher.
However, explicitly adding the snap name to snap refresh will update the snap, regardless of whether the latest revision was previously reverted from or not:
$ snap list --all vlc
Name Version Rev Tracking Publisher Notes
vlc 3.0.5-1 768 stable videolan✓ -
vlc 3.0.6 770 stable videolan✓ disabled
$ sudo snap refresh
All snaps up to date.
$ sudo snap refresh vlc
vlc 3.0.6 from VideoLAN✓ refreshed
A previously used snap that was reverted from will display disabled in the Notes column of the output.
List locally available revisions
By default, the system stores the previous two revisions of a snap locally. The following command lists all revisions locally available for all installed snaps, and also highlights which particular revisions are disabled at the moment:
$ snap list --all
Name Version Rev Tracking Publisher Notes
alacritty 0.8.0 46 latest/stable snapcrafters✪ classic
ascii-patrol 1.7 152 latest/stable mr-gumix disabled
ascii-patrol 1.7 159 latest/stable mr-gumix -
asciinema 2.1.0 32 latest/stable asciinema classic
asciinema 2.0.2 16 latest/stable asciinema disabled,classic
[...]
Please note that ✪ in the output above, shows Star Developers, who are active maintainers in the community.
Adding a snap name to the snap list --all command will return results only for that snap:
$ snap list --all vlc
Name Version Rev Tracking Publisher Notes
vlc 4.0.0-dev-4620 560 edge videolan✓ disabled
vlc 3.0.4 555 edge videolan✓ -
Manually keeping track of which snap revisions available is generally unnecessary. A single revision will only ever be in use at a time, and snapd will remove old revisions automatically.
Create and restore a snapshot
A snapshot is a copy of the user, system and configuration data stored by snapd for one or more snaps on your system, and a snapshot of the data found in both $HOME/snap/<snap-name> and /var/snap/<snap-name> is stored in /var/lib/snapd/snapshots/ (see Data locations for more details).
Snapshots are generated manually with the snap save command and automatically when a snap is removed. A snapshot can be used to backup the state of your snaps, revert snaps to a previous state and to restore a fresh snapd installation to a previously saved state.
The snap save command creates a snapshot for all installed snaps, or if declared individually, specific snaps:
$ sudo snap save
Set Snap Age Version Rev Size Notes
30 core 1.00s 16-2.37~pre1 6229 250B -
30 core18 886ms 18 543 123B -
30 go 483ms 1.10.7 3092 387B -
30 vlc 529ms 3.0.6 770 882kB -
The restore command replaces the current user, system and configuration data with the corresponding data from the specified snapshot:
$ sudo snap restore 30
Restored snapshot #30.
By default, this command restores all the data for all the snaps in a snapshot. You can restore data for specific snaps by simply listing them after the command, and for specific users with the --users=<usernames> argument.
Excluding a snap’s system and configuration data from snap restore is not currently possible.
See Snapshots for further details on creating, exporting, importing and validating snapshots.
Disable and enable snaps
If a snap is temporarily undesired, it can be disabled and later enabled again. This avoids having to remove and reinstall them in the system:
$ sudo snap disable vlc
vlc disabled
$ sudo snap enable vlc
vlc enabled
Remove a snap
To remove a snap from your system, along with its internal user, system and configuration data, use the remove command:
$ sudo snap remove vlc
vlc removed
Add the --no-wait option to return immediately to the command prompt and run the removal in the background.
By default, all of a snap’s revisions are also removed. To remove a specific revision, add the --revision=<revision-number> argument to the remove command.
Prior to removal (except on Ubuntu Core systems), a snap’s internal user, system, and configuration data is saved as a snapshot (snapd 2.39+), and retained for 31 days.
To remove a snap without generating a snapshot, use the additional --purge argument:
$ sudo snap remove vlc --purge
vlc removed
However, a snapshot can be used to restore the state of your snap upon re-installation. See Snapshots for further details.
Last updated a day ago.