1.\" Copyright (c) 1989, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" From: @(#)getgrent.3 8.2 (Berkeley) 4/19/94 33.\" $Id$ 34.\" 35.Dd September 29, 1994 36.Dt GETGRENT 3 37.Os 38.Sh NAME 39.Nm getgrent , 40.Nm getgrnam , 41.Nm getgrgid , 42.Nm setgroupent , 43.\" .Nm setgrfile , 44.Nm setgrent , 45.Nm endgrent 46.Nd group database operations 47.Sh SYNOPSIS 48.Fd #include <grp.h> 49.Ft struct group * 50.Fn getgrent void 51.Ft struct group * 52.Fn getgrnam "const char *name" 53.Ft struct group * 54.Fn getgrgid "gid_t gid" 55.Ft struct group * 56.Fn setgroupent "int stayopen" 57.\" .Ft void 58.\" .Fn setgrfile "const char *name" 59.Ft int 60.Fn setgrent void 61.Ft void 62.Fn endgrent void 63.Sh DESCRIPTION 64These functions operate on the group database file 65.Pa /etc/group 66which is described 67in 68.Xr group 5 . 69Each line of the database is defined by the structure 70.Ar group 71found in the include 72file 73.Aq Pa grp.h : 74.Bd -literal -offset indent 75struct group { 76 char *gr_name; /* group name */ 77 char *gr_passwd; /* group password */ 78 gid_t gr_gid; /* group id */ 79 char **gr_mem; /* group members */ 80}; 81.Ed 82.Pp 83The functions 84.Fn getgrnam 85and 86.Fn getgrgid 87search the group database for the given group name pointed to by 88.Ar name 89or the group id pointed to by 90.Ar gid , 91respectively, returning the first one encountered. Identical group 92names or group gids may result in undefined behavior. 93.Pp 94The 95.Fn getgrent 96function 97sequentially reads the group database and is intended for programs 98that wish to step through the complete list of groups. 99.Pp 100All three routines will open the group file for reading, if necessary. 101.Pp 102The 103.Fn setgroupent 104function 105opens the file, or rewinds it if it is already open. If 106.Fa stayopen 107is non-zero, file descriptors are left open, significantly speeding 108functions subsequent calls. This functionality is unnecessary for 109.Fn getgrent 110as it doesn't close its file descriptors by default. It should also 111be noted that it is dangerous for long-running programs to use this 112functionality as the group file may be updated. 113.Pp 114The 115.Fn setgrent 116function 117is identical to 118.Fn setgroupent 119with an argument of zero. 120.Pp 121The 122.Fn endgrent 123function 124closes any open files. 125.Sh YP/NIS INTERACTION 126When the 127.Xr yp 4 128group database is enabled, the 129.Fn getgrnam 130and 131.Fn getgrgid 132functions use the YP maps 133.Dq Li group.byname 134and 135.Dq Li group.bygid , 136respectively, if the requested group is not found in the local 137.Pa /etc/group 138file. The 139.Fn getgrent 140function will step through the YP map 141.Dq Li group.byname 142if the entire map is enabled as described in 143.Xr group 5 . 144.Sh RETURN VALUES 145The functions 146.Fn getgrent , 147.Fn getgrnam , 148and 149.Fn getgrgid , 150return a pointer to the group entry if successful; if end-of-file 151is reached or an error occurs a null pointer is returned. 152The functions 153.Fn setgroupent 154and 155.Fn setgrent 156return the value 1 if successful, otherwise the value 1570 is returned. 158The functions 159.Fn endgrent 160and 161.Fn setgrfile 162have no return value. 163.Sh FILES 164.Bl -tag -width /etc/group -compact 165.It Pa /etc/group 166group database file 167.El 168.Sh SEE ALSO 169.Fn getpwent 3 , 170.Fn group 5 , 171.Fn yp 4 172.Sh HISTORY 173The functions 174.Fn endgrent , 175.Fn getgrent , 176.Fn getgrnam , 177.Fn getgrgid , 178and 179.Fn setgrent 180appeared in 181.At v7 . 182The functions 183.Fn setgrfile 184and 185.Fn setgroupent 186appeared in 187.Bx 4.3 Reno . 188.Sh COMPATIBILITY 189The historic function 190.Fn setgrfile , 191which allowed the specification of alternate password databases, has 192been deprecated and is no longer available. 193.Sh BUGS 194The functions 195.Fn getgrent , 196.Fn getgrnam , 197.Fn getgrgid , 198.Fn setgroupent 199and 200.Fn setgrent 201leave their results in an internal static object and return 202a pointer to that object. Subsequent calls to 203the same function 204will modify the same object. 205