Question: I am using Ubuntu 18.04 and my GNOME Shell version is 3.28. When I opened Ubuntu Software and checked the installed software, I found that there are 2 different versions of GNOME runtime (3.26 and 3.28):

[![Ubuntu Software](https://i.stack.imgur.com/bux6N.png)](https://i.stack.imgur.com/bux6N.png)

1. How to check which one of them is running?
2. Is it OK to uninstall one of them (the one that is not used)?

Answer: 
The GNOME runtimes contain the GNOME stack and shared libraries that are needed by snap apps (snaps) and their version number may be different than the GNOME Shell version number.

Due to the nature of snaps, every time there is a new snap update, a new stack and libraries is downloaded. The old ones don't get automatically deleted, but they get disabled. To get a list of your installed snaps, run:

```
snap list --all

```

You will see that some snaps have a `disabled` tag. These are snaps that you can safely remove by running:

```
snap remove <snap-name> --revision <rev-num>

```

where `<snap-name>` is the name of the app as it shows in the `snap list --all` command output and `<rev-num>` is the revision number of the app under the `Rev` column of `snap list --all`.

You will probably find that some revisions of GNOME 3.26 and 3.28 runtimes are enabled and some disabled. In that case, you may remove the disabled revisions, as described above, but you shouldn't remove the enabled ones, as both versions of GNOME 3.26 and 3.28 runtimes are needed by your snaps in order for them to work.
In addition to the [other answer](https://askubuntu.com/a/1162731/618353), to clean all old versions of snaps, try:

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

```

Adapted from this Super User answer: [How to remove old version of installed snaps](https://superuser.com/questions/1310825/how-to-remove-old-version-of-installed-snaps/1356803#1356803)