irix - groups (1)

     groups - show group memberships

     groups [user]

     The groups	command	shows the groups to which you or the optionally
     specified user belong.  Each user belongs to a group specified in the
     password file /etc/passwd and possibly to other groups as specified in
     the file /etc/group.  Invoking groups without a user specified executes a
     getgroups system call, which returns the grouplist	of which the process
     is	currently a member.  This list will contain only the effective group
     ID	unless a multgrps call has been	executed; in that case it will contain
     all groups	in /etc/group to which the user	belongs.  If you do not	own a
     file but belong to	the group which	owns it	then you are granted group
     access to the file.

     When creating a new file, if the underlying filesystem was	mounted	with
     the BSD file creation semantics flag [see fstab(4)] or the	S_ISGID	bit is
     set [see chmod(2)]	on the parent directory, then the group	ID of the new
     file is set to the	group ID of the	parent directory, otherwise it is set
     to	the effective group ID of the calling process.

     The maximum number	of groups of which a process may be a member is
     defined (as an lbootable option) in /var/sysgen/master.d/kernel, named
     NGROUPS_MAX.

     multgrps(1), newgrp(1), id(1), setgroups(2), open(2)

     /etc/passwd, /etc/group