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.
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.
Commands: addgroup(8), adduser(8), groups(1), passwd(1)