group(5)

group - user group file

The /etc/group file is a text file that defines the groups on the system. There is one entry per line, with the following format:

group_name	the name of the group.
password	the (encrypted) group password. If this field is empty, no password is needed.
GID	the numeric group ID.
user_list	a list of the usernames that are members of this group, separated by commas.

As the 4.2BSD initgroups(3) man page says: no one seems to keep /etc/group up-to-date.

chgrp(1), gpasswd(1), groups(1), login(1), newgrp(1), sg(1), getgrent(3), getgrnam(3), gshadow(5), passwd(5), vigr(8)

newgrp(1), fgetgrent(3), getgrent(3), getgrent_r(3), getgrnam(3), getgrouplist(3), group_member(3), putgrent(3), credentials(7), passwd(1), passwd(5), grpck(8), pwck(8), vipw(8), cppw(8), aer(5), sync-accounts(5), sync-accounts(8), ftpd(8), nscd(8), conflict(8mh), conflict(8), mknetid(8), ftpasswd(8), , kftpd(8), opieftpd(8)