Different UNIX operating systems implement the group concept in various ways. Ubuntu uses a scheme called UPG (user private group) in which the default is that all users are assigned to a group with their own name. (The user’s username and group name are identical.) All the groups on a system are listed in
Here is an example of a portion of the
matthew@seymour:~$ cat /etc/grouproot:x:0:daemon:x:1:bin:x:2:sys:x:3:adm:x:4:matthewtty:x:5:disk:x:6:mail:x:8:news:x:9:fax:x:21:matthewvoice:x:22:cdrom:x:24:matthewfloppy:x:25:matthewtape:x:26:matthewwww-data:x:33:crontab:x:107:ssh:x:109:admin:x:115:matthewsaned:x:116:gdm:x:119:matthew:x:1000:ntp:x:122:
In this example, you see a number of groups, mostly ...