id
id [user]
Risk: Safe
What it does
Shows a user's number and every group (team) they belong to.
When to use it
To check who you are and which keys your teams give you.
Example
$ idYou: uid 1000, groups you and sudo.
$ id ainaAnother user's numbers and groups.
$ groups ainaJust the group names.
Learn it in: Users, groups and sudo · Official docs