This file is named /etc/group and is similar to the password and shadow files; in other words, it is an ASCII file consisting of colon-separated strings. It contains definitions for all the groups that are used on the system and, by default, looks like the one shown here: hydrogen# cat /etc/group root::0:root other::1: bin::2:root,bin,daemon sys::3:root,bin,sys,adm adm::4:root,adm,daemon uucp::5:root,uucp mail::6:root tty::7:root,tty,adm lp::8:root,lp,adm nuucp::9:root,nuucp staff::10: daemon::12:root,daemon sysadmin::14: nobody::60001: noaccess::60002: nogroup::65534: hydrogen# The field entries are as follows. Field 1: Group Name This is the actual group name. Field 2: Group Password This field is largely historical and now rarely used. It can be empty. It can contain an invalid encrypted password, such as an "*." It can contain a valid encrypted password (13 characters). Unfortunately, there isn't any way to get a password in here other than manually inserting an already encrypted password. The effects of this field vary depending upon whether you are a member of the group or not. Let's leave group passwords for now and revisit them in the following section, "Primary and Secondary Groups." Field 3: Group Identity Number Similar to the UID, the GID is used to store the numerical ID of a group. The value should be less than 60,000 for compatibility with other systems. Field 4: Group User List This contains a comma-separated list of users who are allowed to be in this group. It is used in conjunction with newgrp, which we'll look at in the following section. |