How do I find out in which groups Ubuntu Linux users belong to? How do I find out Ubuntu Linux group membership for a particular user named tom?

You can use any one of the following command to list a groups a user belongs to:

a) id command – Display real and effective user and group IDs.

b) groups command – Display the groups a user is in on Ubuntu Linux.

Ubuntu: See which groups your Linux user belongs to

Open the Terminal app or login to the remote server over the ssh based session. Type the following id command
$ id -Gn

To display the groups a user named ‘tom’ is in on Ubuntu Linux, enter:
$ id -Gn tom

You can also use deprecated groups command as follows:
$ groups
$ groups tom

Sample outputs:

See also

• Linux / Unix: groups Command Examples
• Linux / Unix: id Command Examples
• Man pages – groups(1),id(1)