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

I think the easiest way is the following steps, you won't need to install any package or software:

1. First, you find out the GID of the group that you want to know the users, there are a lot of ways for that: cat /etc/group (the last column is the GID) id user (the user is someone who belongs to the group)

2. Now you will list all the user on the file /etc/passwd, but you will apply some filters with the following sequel of commands to get just the members of the previous group.

cut -d: -f1,4 /etc/passwd |grep GID (the GID is the number you got from the step 1)

cut command will select just some "columns" of the file, the parameter d sets the delimiter ":" in this case, the parameter -f selects the "fields" (or columns) to be shown 1 and 4 in out case (on the file /etc/passwd, the 1º column is the name of the user and the 4º is the GID of the group which the user belongs), to finalize the |grep GID will filter just the group (on the 4º column) that you had chosen.