How to list all users in a Linux group?

Question

How do I list all members of a group in Linux (and possibly other unices)?

Answer 1

getent group groupname | awk -F: '{print $4}' | tr , '\n'

This has 3 parts:

1 - getent group groupname shows the line of the group in "/etc/group" file. Alternative to cat /etc/group | grep groupname.

2 - awk print's only the members in a single line separeted with ',' .

3 - tr replace's ',' with a new line and print each user in a row.

4 - Optional: You can also use another pipe with sort, if the users are too many.

Regards

Answer 2

There is a handy Debian and Ubuntu package called 'members' that provides this functionality:

Description: Shows the members of a group; by default, all members members is the complement of groups: whereas groups shows the groups a specified user belongs to, members shows users belonging to a specified group.

... You can ask for primary members, secondary members, both on one line, each on separate lines.