The /etc/group database contains information for each
group in the following form:
groupname:password:gid:user-list
The following list describes the required fields:
groupname
The name of the group.
password
The group's password, in an encrypted form.
This field may be empty.
gid
An integer representing the group; each
group is assigned a unique integer.
user-list
The user list is a comma-separated list of
users allowed in the group.
