First steps with Ubuntu Core
The Ubuntu Core environment is much like a vanilla Ubuntu server environment managed remotely via SSH.
To connect to Ubuntu Core, use your Ubuntu SSO username and the Ubuntu Core device IP address, as provided by Ubuntu Core if it’s connected to a display:
$ ssh <sso-username>@<device-ip-address>
You may need to specify the location of the private SSH key linked to your Ubuntu SSO registered public key:
$ ssh -i <path-to-private-key> <sso-username>@<device-ip-address>
The main difference between a classic Ubuntu installation and Ubuntu Core is that Ubuntu Core’s system configuration, package management, and update control is governed entirely by snapd, the snap daemon.
Snap features are comprehensively explained in the Snap documentation, but we’ll cover some basic operations below:
You can list which snaps are installed on your Ubuntu Core system with
$ snap list Name Version Rev Tracking Publisher Notes core20 20 768 latest/beta canonical✓ base pc 20-0.4 108 20/beta canonical✓ gadget pc-kernel 5.4.0-47.51.1 598 20/beta canonical✓ kernel snapd 2.46.1 9279 latest/beta canonical✓ snapd $
The above shows the standard set of snaps in a default Ubuntu Core 20 installation. For more details on what these do, see Snaps in Ubuntu Core.
As Ubuntu Core is a minimal installation, one of the first things you might want to install is a text editor. You can search for snaps using
snap find, or consult the Snap Store. Nano-strict is a good choice because it’s strictly confined, as required for Ubuntu Core, and useful:
$ snap install nano-strict
By default, Ubuntu Core defaults to disabling access to most resources, including writing files to your home directory.
Permissions in snap and Ubuntu Core are handled by interfaces. You can see which interfaces nano-strict needs with the
snap connections command:
$ snap connections nano-strict Interface Plug Slot Notes home nano-strict:home - - removable-media nano-strict:removable-media - -
Connecting the home interface between Ubuntu Core and nano-strict will allow you to save files to your home directory. This is accomplished with the
snap connect command:
$ snap connect nano-strict:home :home
after which you can verify that you are connected to your home directory:
$ snap connections nano-strict Interface Plug Slot Notes home nano-strict:home :home manual removable-media nano-strict:removable-media - -
After running the above command, you will be able use the
nano-strict command to create and edit text files in your home directory!
:home syntax denotes the home slot on Ubuntu Core. For more information on how to work with interfaces, see Interface management in the snap documentation.
To remove a snap from your system, along with its internal user, system and configuration data, use the
snap remove command:
$ sudo snap remove nano-strict nano-strict removed
For more information on how to work with snaps, including how to control daemons/servers, how to make data snapshots and how to install specific revisions, see the Snap Documentation .
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