First steps with Ubuntu Core
In use, 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 promoted by Ubuntu Core if it’s connected to a display:
$ ssh <sso-username>@<device-ip-address>
You may need to optionally specifiy the location of the private SSH key linked to the 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 entirely governed 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 with snap list:
$ 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 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 connect command:
$ snap connect nano-strict:home :home $ 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 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 .