To print the groups a user is in use groups command. For example print all groupname vivek user belongs to:
Sample output:
Code:
vivek : vivek adm dialout cdrom floppy audio dip video plugdev scanner netdev lpadmin powerdev admin dba vboxusers
However, to find out all members of a group, type following
Code:
egrep "^groupname" /etc/group
egrep "^adm" /etc/group
egrep "^ftpusers" /etc/group
HTH