How to remove old version of installed snaps

Here's a short script which will remove all old versions of snaps. This will only keep the current active version, which should recover you some disk space:

#!/bin/bash
# Removes old revisions of snaps
# CLOSE ALL SNAPS BEFORE RUNNING THIS
set -eu

LANG=C snap list --all | awk '/disabled/{print $1, $3}' |
    while read snapname revision; do
        snap remove "$snapname" --revision="$revision"
    done

The "Close snaps" is there because you may not have restarted an application before you updated. So it's possible you're actually running a revision which is to be removed by the script.

A version of the script from another answer, as a one-liner, without the awk dependency:

snap list --all | while read snapname ver rev trk pub notes; do if [[ $notes = *disabled* ]]; then snap remove "$snapname" --revision="$rev"; fi; done

This likely requires bash or a compatible shell with the [[ construct.

Starting from snap v2.34 and later, you can set the maximum number of snap revisions stored for each package by setting the refresh.retain option—it can only be a number between 2 and 20 and has a default value of 3.

sudo snap set system refresh.retain=2 

The snapd docs on versions state that the outdated revisions should be automatically removed so that no more than the last two revisions are installed. However, I also saw more than two versions of my snaps installed.

You can list all the revisions with snap list --all to see something like:

Name     Version                  Rev   Tracking  Developer  Notes
core     16-2.31.2                4206  stable    canonical  core,disabled
core     16-2.32.3                4407  stable    canonical  core,disabled
core     16-2.32.5                4486  stable    canonical  core
spotify  1.0.70.399.g5ffabd56-26  5     stable    spotify    disabled
spotify  1.0.72.117.g6bd7cc73-35  6     stable    spotify    disabled
spotify  1.0.77.338.g758ebd78-41  13    stable    spotify    -

You can remove individual revisions with

snap remove spotify --revision=5

This is safe even for the disabled revisions of core and other dependencies, and snap remove with an explicit --revision=... even prevents you from removing non-disabled snaps.

The code @popey shared in their answer actually fails sometimes as some broken packages don't have the version info. So I modified the code to overcome this.

#!/bin/bash
# Removes old revisions of snaps
# CLOSE ALL SNAPS BEFORE RUNNING THIS
set -eu

snapsToRemove=$(LANG=en_US.UTF-8 snap list --all | awk '/disabled/{print $1, $2, $3}')

while read snapname version revision; do
    if [[ "$revision" == *[a-zA-z]* ]]; then
        # Version field is empty. Revision is in second field
        revision=$version
    fi
        snap remove "$snapname" --revision="$revision"
done <<< $snapsToRemove