| Group | 
gid | 
Description | 
| root | 
0 | 
This is root's primary group. | 
| daemon | 
1 | 
A group for non-root daemons. | 
| bin | 
2 | 
This group exists for historical reasons and some programs
  won't run without it. | 
| sys | 
3 | 
This group exists for historical reasons and some programs
  won't run without it. | 
| adm | 
4 | 
Most of the log files (in /var/log)
  are group readable by users who belong
  to his group. You can add users who need to monitor such log
  files to this group. Note though that sometimes private
  information can be accidentally included in logs, like
  passwords when connecting via PPP over a Modem.  This should
  not happen (the scripts that write the logs should identify
  these as not being echoed) but the potential for mistakes is there. | 
| tty | 
5 | 
The terminal devices with names beginning with
  /dev/tty are group accessible
  to group tty. Programs such as write and
  wall need access to /dev/tty and they set their
  group id (sgid) to tty. | 
| disk | 
6 | 
The disk device nodes are group accessible to disk so
  that programs that need access to them will set their group ID to be
  disk. This group has write access to all the raw disk
  devices (/dev/hd* and /dev/sd*), so assigning users to group
  disk is both dangerous and a security risk. | 
| lp | 
7 | 
Jobs associated with the lp (printer) daemon
  (lpd) are group accessible to the lp group so
  that lpd
  can access them without being root. | 
| mail | 
8 | 
mailbox spool directories belong to group mail, MUA software runs
setgid mail. This makes dot locking possible. Also, mailboxes must be
writeable by group mail (Policy Manual, 3.1.1.1, 5.6). | 
| news | 
9 | 
standard group for user news. Why does news have its own group, and
many of the other daemon uids don't? | 
| uucp | 
10 | 
uucp jobs are group accessible to uucp. | 
| proxy | 
13 | 
web cache files are group accessible to proxy. | 
| kmem | 
15 | 
/proc/kmem is group accessible to kmem. Programs that need access are
sgid kmem. | 
| dialout | 
20 | 
ppp- and isdn device nodes are group accessible to dialout. Include
users allowed to initiate dialout in this group. | 
| fax | 
21 | 
fax jobs are group accessible to fax. | 
| voice | 
22 | 
voice messages are group accessible to voice (vgetty) | 
| cdrom | 
24 | 
The cdrom group is used to control who can access the
CD-ROM. | 
| floppy | 
25 | 
  | 
| tape | 
26 | 
for device nodes. Include users allowed to access these in the
appropriate groups. | 
| sudo | 
27 | 
  | 
| audio | 
29 | 
for device nodes. Include users allowed to access sound in this group | 
| dip | 
30 | 
For daemons running under their own uid/gid. Why are these static? | 
| majordom | 
30 | 
For daemons running under their own uid/gid. Why are these static? | 
| postgres | 
32 | 
For daemons running under their own uid/gid. Why are these static? | 
| www-data | 
33 | 
This has been discussed in the past, and the discussion is not finally
finished. Today, www data files belong to this group and the web
servers run with that group, thus being able to write the files.
This has been considered a security hole, but was not yet changed. | 
| backup | 
34 | 
  | 
| msql | 
36 | 
For daemons running under their own uid/gid. Why are these static? | 
| operator | 
37 | 
  | 
| list | 
38 | 
  | 
| irc | 
39 | 
For daemons running under their own uid/gid. Why are these
static? | 
| src | 
40 | 
This group is intended for users who need to access source
code, including files in /usr/src. Users in this group can thus manage
system source code. Also, this group is the default group for
access to the CSV repository in /var/lib/csv. | 
| gnats | 
41 | 
For daemons running under their own uid/gid. Why are these static? | 
| shadow | 
42 | 
Programs that should be able to access the shadow passwords are sgid
shadow.
 | 
| utmp | 
43 | 
Programs that should be able to access utmp are sgid utmp. | 
| video | 
44 | 
  | 
| staff | 
50 | 
This group is used to control access to
          /usr/local. Add users to this if they should be
          able to write to /usr/local and
         /var/local. | 
| games | 
60 | 
games that store user independent high score values in /var/lib/games
are sgid games | 
| qmail | 
70 | 
used for qmail | 
| users | 
100 | 
All users belong to this group. Place files that all users
          should have access to in this group. |