1.\" $NetBSD: group.5,v 1.16 2003/10/13 15:36:34 agc Exp $ 2.\" 3.\" Copyright (c) 1980, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" Portions Copyright(c) 1994, Jason Downs. All rights reserved. 31.\" 32.\" Redistribution and use in source and binary forms, with or without 33.\" modification, are permitted provided that the following conditions 34.\" are met: 35.\" 1. Redistributions of source code must retain the above copyright 36.\" notice, this list of conditions and the following disclaimer. 37.\" 2. Redistributions in binary form must reproduce the above copyright 38.\" notice, this list of conditions and the following disclaimer in the 39.\" documentation and/or other materials provided with the distribution. 40.\" 41.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS 42.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 43.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 44.\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, 45.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 46.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 47.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 48.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51.\" SUCH DAMAGE. 52.\" 53.\" @(#)group.5 8.3 (Berkeley) 4/19/94 54.\" 55.Dd November 17, 2000 56.Dt GROUP 5 57.Os 58.Sh NAME 59.Nm group 60.Nd format of the group permissions file 61.Sh DESCRIPTION 62The 63.Nm 64file 65.Pa /etc/group 66is the local source of group information. 67It can be used in conjunction with the Hesiod domain 68.Sq group , 69and the 70.Tn NIS 71maps 72.Sq group.byname 73and 74.Sq group.bygid , 75as controlled by 76.Xr nsswitch.conf 5 . 77.Pp 78The 79.Nm 80file consists of newline separated 81.Tn ASCII 82records, one per group, containing four colon 83.Ql \&: 84separated fields. 85Each line has the form: 86.Dl group:passwd:gid:[member[,member]...] 87.Pp 88These fields are as follows: 89.Bl -tag -width password -offset indent -compact 90.It Em group 91Name of the group. 92.It Em passwd 93Group's 94.Em encrypted 95password. 96.It Em gid 97The group's decimal ID. 98.It Em member 99Group members. 100.El 101.Pp 102The 103.Em group 104field is the group name used for granting file access to users 105who are members of the group. 106.Pp 107The 108.Em gid 109field is the number associated with the group name. 110They should both be unique across the system (and often 111across a group of systems) since they control file access. 112.Pp 113The 114.Em passwd 115field 116is an optional 117.Em encrypted 118password. 119This field is rarely used 120and an asterisk is normally placed in it rather than leaving it blank. 121.Pp 122The 123.Em member 124field contains the names of users granted the privileges of 125.Em group . 126The member names are separated by commas without spaces or newlines. 127A user is automatically in a group if that group was specified 128in their 129.Pa /etc/passwd 130entry and does not need to be added to that group in the 131.Pa /etc/group 132file. 133.Pp 134The group with the name 135.Dq wheel 136has a special meaning to the 137.Xr su 1 138command: if it exists and has any members, only users listed in that group 139are allowed to 140.Nm su 141to 142.Dq root . 143.Sh HESIOD SUPPORT 144If 145.Sq dns 146is specified for the 147.Sq group 148database in 149.Xr nsswitch.conf 5 , 150then 151.Nm 152lookups occur from the 153.Sq group 154Hesiod domain. 155.Sh NIS SUPPORT 156If 157.Sq nis 158is specified for the 159.Sq group 160database in 161.Xr nsswitch.conf 5 , 162then 163.Nm 164lookups occur from the 165.Sq group.byname 166and 167.Sq group.bygid 168.Tn NIS 169map. 170.Sh COMPAT SUPPORT 171If 172.Sq compat 173is specified for the 174.Sq group 175database, and either 176.Sq dns 177or 178.Sq nis 179is specified for the 180.Sq group_compat 181database in 182.Xr nsswitch.conf 5 , 183then the 184.Nm 185file may also contain lines of the format 186.Pp 187+name:*:: 188.Pp 189which causes the specified group to be included from the 190.Sq group 191Hesiod domain 192or the 193.Sq group.byname 194.Tn NIS 195map (respectively). 196.Pp 197If no group name is specified, or the plus sign 198.Pq Dq \&+ 199appears alone 200on line, all groups are included from the 201Hesiod domain or the 202.Tn NIS 203map. 204.Pp 205Hesiod or 206.Tn NIS 207compat references may appear anywhere in the file, but the single 208plus sign 209.Pq Dq \&+ 210form should be on the last line, for historical reasons. 211Only the first group with a specific name encountered, whether in the 212.Nm 213file itself, or included via Hesiod or 214.Tn NIS , 215will be used. 216.Sh FILES 217.Bl -tag -width /etc/group -compact 218.It Pa /etc/group 219.El 220.Sh SEE ALSO 221.Xr passwd 1 , 222.Xr su 1 , 223.Xr setgroups 2 , 224.Xr crypt 3 , 225.Xr initgroups 3 , 226.Xr nsswitch.conf 5 , 227.Xr passwd 5 , 228.Xr yp 8 229.Sh HISTORY 230A 231.Nm 232file format appeared in 233.At v6 . 234.Pp 235The 236.Tn NIS 237file format first appeared in SunOS. 238.Pp 239The Hesiod support first appeared in 240.Nx 1.4 . 241.Sh BUGS 242The 243.Xr passwd 1 244command does not change the 245.Nm group 246passwords. 247