How to list files installed by a snap package?

Snaps are compressed squashfs files, which typically get 'installed' to /var/lib/snapd/snaps. So if you snap install ohmygiraffe you'll find a file called /var/lib/snapd/snaps/ohmygiraffe_3.snap.

If you'd never installed a snap before then you'll also have a core snap which lives at the same location.

If you're interested in seeing what's inside that snap, look in /snap/<snapname>/<current>/. Note that you're peering into the snap, the contents aren't unpacked onto your filesystem.

The only other thing you'll find is a .desktop file in /var/lib/snapd/desktop/applications.

Once your snap has been run, you may also find data in ~/snap/<snapname>.

Snaps are standalone squashfs images, which means listing what they install is as simple as listing the contents of the image. These images get mounted into place at /snap/<snapname>/<snap revision>, although you can just use /snap/<snapname>/current for the currently-active revision, e.g.:

$ ls -lR /snap/<snapname>/current/