1. /etc/group
   - lists the groups in format: name:x:grp_id:
   - place comma seperated usernames after "grp_id:"
2. /etc/psswd
   - lists the users in format: name:x:usr_id:grp_id:
   - update grp_id

i/etc/group lets me execute stuff with the group permission,
but doesn't give me file rights like /etc/psswd