264 lines
6.8 KiB
Groff
264 lines
6.8 KiB
Groff
.\" $NetBSD: group.5,v 1.19 2009/05/13 22:33:59 wiz Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" Portions Copyright(c) 1994, Jason Downs. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
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.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
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.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)group.5 8.3 (Berkeley) 4/19/94
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.\"
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.Dd June 21, 2007
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.Dt GROUP 5
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.Os
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.Sh NAME
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.Nm group
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.Nd format of the group permissions file
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.Sh DESCRIPTION
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The
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.Nm
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file
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.Pa /etc/group
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is the local source of group information.
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It can be used in conjunction with the Hesiod domain
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.Sq group ,
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and the
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.Tn NIS
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maps
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.Sq group.byname
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and
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.Sq group.bygid ,
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as controlled by
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.Xr nsswitch.conf 5 .
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.Pp
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The
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.Nm
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file consists of newline separated
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.Tn ASCII
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records, usually one per group, containing four colon
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.Ql \&:
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separated fields.
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Each line has the form:
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.Dl group:passwd:gid:[member[,member]...]
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.Pp
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These fields are as follows:
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.Bl -tag -width password -offset indent -compact
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.It Em group
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Name of the group.
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.It Em passwd
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Group's
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.Em encrypted
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password.
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.It Em gid
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The group's decimal ID.
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.It Em member
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Group members.
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.El
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.Pp
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The
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.Em group
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field is the group name used for granting file access to users
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who are members of the group.
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.Pp
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The
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.Em gid
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field is the number associated with the group name.
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They should both be unique across the system (and often
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across a group of systems) since they control file access.
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.Pp
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The
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.Em passwd
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field
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is an optional
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.Em encrypted
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password.
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This field is rarely used
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and an asterisk is normally placed in it rather than leaving it blank.
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.Pp
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The
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.Em member
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field contains the names of users granted the privileges of
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.Em group .
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The member names are separated by commas without spaces or newlines.
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A user is automatically in a group if that group was specified
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in their
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.Pa /etc/passwd
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entry and does not need to be added to that group in the
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.Pa /etc/group
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file.
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.Pp
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Very large groups can be accommodated over multiple lines by specifying the
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same group name in all of them; other than this, each line has an identical
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format to that described above.
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This can be necessary to avoid the record's length limit, which is currently
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set to 1024 characters.
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Note that the limit can be queried through
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.Xr sysconf 3
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by using the
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.Li _SC_GETGR_R_SIZE_MAX
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parameter.
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For example:
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.Bd -literal -offset indent
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biggrp:*:1000:user001,user002,user003,...,user099,user100
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biggrp:*:1000:user101,user102,user103,...
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.Ed
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.Pp
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The group with the name
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.Dq wheel
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has a special meaning to the
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.Xr su 1
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command: if it exists and has any members, only users listed in that group
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are allowed to
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.Nm su
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to
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.Dq root .
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.Sh HESIOD SUPPORT
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If
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.Sq dns
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is specified for the
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.Sq group
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database in
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.Xr nsswitch.conf 5 ,
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then
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.Nm
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lookups occur from the
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.Sq group
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Hesiod domain.
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.Sh NIS SUPPORT
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If
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.Sq nis
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is specified for the
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.Sq group
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database in
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.Xr nsswitch.conf 5 ,
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then
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.Nm
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lookups occur from the
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.Sq group.byname
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and
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.Sq group.bygid
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.Tn NIS
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map.
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.Sh COMPAT SUPPORT
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If
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.Sq compat
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is specified for the
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.Sq group
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database, and either
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.Sq dns
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or
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.Sq nis
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is specified for the
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.Sq group_compat
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database in
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.Xr nsswitch.conf 5 ,
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then the
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.Nm
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file may also contain lines of the format
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.Pp
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+name:*::
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.Pp
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which causes the specified group to be included from the
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.Sq group
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Hesiod domain
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or the
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.Sq group.byname
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.Tn NIS
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map (respectively).
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.Pp
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If no group name is specified, or the plus sign
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.Pq Dq \&+
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appears alone
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on line, all groups are included from the
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Hesiod domain or the
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.Tn NIS
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map.
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.Pp
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Hesiod or
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.Tn NIS
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compat references may appear anywhere in the file, but the single
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plus sign
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.Pq Dq \&+
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form should be on the last line, for historical reasons.
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Only the first group with a specific name encountered, whether in the
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.Nm
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file itself, or included via Hesiod or
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.Tn NIS ,
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will be used.
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.Sh FILES
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.Bl -tag -width /etc/group -compact
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.It Pa /etc/group
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.El
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.Sh SEE ALSO
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.Xr newgrp 1 ,
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.Xr passwd 1 ,
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.Xr su 1 ,
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.Xr setgroups 2 ,
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.Xr crypt 3 ,
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.Xr initgroups 3 ,
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.Xr nsswitch.conf 5 ,
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.Xr passwd 5 ,
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.Xr yp 8
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.Sh HISTORY
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A
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.Nm
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file format appeared in
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.At v6 .
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.Pp
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The
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.Tn NIS
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file format first appeared in SunOS.
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.Pp
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The Hesiod support first appeared in
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.Nx 1.4 .
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.Sh BUGS
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The
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.Xr passwd 1
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command does not change the
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.Nm group
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passwords.
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