group(4) Kernel Interfaces Manual group(4)
NAME
group - Group file
DESCRIPTION
The /etc/group database contains the following information for each group: Group name Encrypted password Numerical group ID A comma-sepa-
rated list of all users allowed in the group
Note: Do not put any spaces between a comma and a username; otherwise, the username following the comma will not be made a part of the
desired group.
The /etc/group file is an ASCII file, with the fields separated by colons. Each group is separated from the next by a new line. If the
password field is null, no password is demanded.
Because of the encrypted passwords, it can and does have general read permission and can be used, for example, to map numerical group IDs
to names.
Note that commands or scripts used for adding users to groups are subject to the 225 character limit on line lengths. However, you can
split lines as appropriate.
RESTRICTIONS
Increasing the number of groups that a user is in beyond 16 can affect services that use ONC RPC. Tru64 UNIX ONC RPC supports up to 32
groups for compatibility with ULTRIX Version 4.2 and higher. Other vendors may support only 16 groups. ULTRIX versions before 4.2 support
up to 8 groups. Users who increase their group membership beyond 8 or 16 groups will not be able to NFS mount file systems from servers
that only support 8 or 16 groups over NFS. In addition, if root group membership is increased beyond 8 or 16, the NIS service will not work
in a mixed NIS server environment where the servers support only 8 or 16 groups. The addgroup command limits the length of a group name to
eight characters or less.
FILES
/etc/group
RELATED INFORMATION
Commands: addgroup(8), groupadd(8), adduser(8), groups(1), passwd(1)
Functions: setgroups(2)
Routines: initgroups(3)
Files: passwd(4)
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group(4)
