.\" Portions Copyright (c) 2001, 2006 Apple Computer, Inc. All Rights Reserved.
.\" $NetBSD: group.5,v 1.4 1995/07/28 06:41:39 phil Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\" Portions Copyright(c) 1994, Jason Downs. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)group.5 8.3 (Berkeley) 4/19/94
.\"
.Dd July 18, 1995
.Dt GROUP 5
.Os "Mac OS X"
.Sh NAME
.Nm group
.Nd format of the group permissions file
.Sh DESCRIPTION
.Pp
The file
.Aq Pa /etc/group
consists of newline separated
.Tn ASCII
records, one per group, containing four colon
.Ql \&:
separated fields. These fields are as follows:
.Bl -tag -width password -offset indent -compact
.It group
Name of the group.
.It passwd
Group's
.Em encrypted
password.
.It gid
The group's decimal ID.
.It member
Group members.
.El
.Pp
The
.Ar group
field is the group name used for granting file access to users
who are members of the group.
The
.Ar gid
field is the number associated with the group name.
They should both be unique across the system (and often
across a group of systems) since they control file access.
The
.Ar passwd
field
is an optional
.Em encrypted
password.
This field is rarely used
and an asterisk is normally placed in it rather than leaving it blank.
The
.Ar member
field contains the names of users granted the privileges of
.Ar group .
The member names are separated by commas without spaces or newlines.
A user is automatically in a group if that group was specified
in their
.Pa /etc/passwd
entry and does not need to be added to that group in the
.Pa /etc/group file.
.\" .Pp
.\" When the system reads the file
.\" .Pa /etc/group
.\" the fields are read into the structure
.\" .Fa group
.\" declared in
.\" .Aq Pa grp.h :
.\" .Bd -literal -offset indent
.\" struct group {
.\" char *gr_name; /* group name */
.\" char *gr_passwd; /* group password */
.\" int gr_gid; /* group id */
.\" char **gr_mem; /* group members */
.\" };
.\" .Ed
.Sh INTERACTION WITH DIRECTORY SERVICES
Processes generally find group records using one of the
.Xr getgrent 3
family of functions.
On Mac OS X, these functions interact with the
.Xr DirectoryService 8
daemon,
which reads the /etc/group file as well as searching other directory information services
to determine groups and group membership.
.Sh FILES
.Bl -tag -width /etc/group -compact
.It Pa /etc/group
.El
.Sh SEE ALSO
.Xr passwd 1 ,
.Xr setgroups 2 ,
.Xr crypt 3 ,
.Xr getgrent 3 ,
.Xr initgroups 3 ,
.Xr passwd 5 ,
.Xr DirectoryService 8
.Sh BUGS
The
.Xr passwd 1
command does not change the
.Nm group
passwords.
.Sh HISTORY
A
.Nm
file format appeared in
.At v6 .