Apple Mac OS X Server (Administrator’s Guide) - Manual (Page 131)

Users and Groups 131
The following table characterizes the group accounts that are created automatically when you
install Mac OS X.
Predefined
group name
Group ID Use
admin 80 The group to which users with administrator privileges
belong.
bin 7 A group that owns all binary files.
daemon 1 A group used by system services.
dialer 68 A group for controlling access to modems on a server.
guest 31
kmem 2 A legacy group used to control access to reading kernel
memory.
mail 6 The group historically used for access to local UNIX mail.
mysql 74 The group that the MySQL database server uses for its
processes that handle requests.
network 69 This group has no specific meaning.
nobody -2 A group used by system services.
nogroup -1 A group used by system services.
operator 5 This group has no specific meaning.
smmsp 25 The group used by sendmail.
staff 20 The default group into which UNIX users are traditionally
placed.
sys 3 This group has no specific meaning.
tty 4 A group that owns special files, such as the device file
associated with an SSH or telnet user.
unknown 99 The group used when the system doesn’t know about the
hard drive.
utmp 45 The group that controls what can update the system’s list of
logged-in users.
uucp 66 The group used to control access to UUCP spool files.