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.\" $FreeBSD$ 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 LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.Fd #include <sys/types.h> 51.Fd #include <grp.h> 52.Ft struct group * 53.Fn getgrent void 54.Ft struct group * 55.Fn getgrnam "const char *name" 56.Ft struct group * 57.Fn getgrgid "gid_t gid" 58.Ft int 59.Fn setgroupent "int stayopen" 60.\" .Ft void 61.\" .Fn setgrfile "const char *name" 62.Ft int 63.Fn setgrent void 64.Ft void 65.Fn endgrent void 66.Sh DESCRIPTION 67These functions operate on the group database file 68.Pa /etc/group 69which is described 70in 71.Xr group 5 . 72Each line of the database is defined by the structure 73.Ar group 74found in the include 75file 76.Aq Pa grp.h : 77.Bd -literal -offset indent 78struct group { 79 char *gr_name; /* group name */ 80 char *gr_passwd; /* group password */ 81 int gr_gid; /* group id */ 82 char **gr_mem; /* group members */ 83}; 84.Ed 85.Pp 86The functions 87.Fn getgrnam 88and 89.Fn getgrgid 90search the group database for the given group name pointed to by 91.Ar name 92or the group id pointed to by 93.Ar gid , 94respectively, returning the first one encountered. Identical group 95names or group gids may result in undefined behavior. 96.Pp 97The 98.Fn getgrent 99function 100sequentially reads the group database and is intended for programs 101that wish to step through the complete list of groups. 102.Pp 103All three routines will open the group file for reading, if necessary. 104.Pp 105The 106.Fn setgroupent 107function 108opens the file, or rewinds it if it is already open. If 109.Fa stayopen 110is non-zero, file descriptors are left open, significantly speeding 111functions subsequent calls. This functionality is unnecessary for 112.Fn getgrent 113as it doesn't close its file descriptors by default. It should also 114be noted that it is dangerous for long-running programs to use this 115functionality as the group file may be updated. 116.Pp 117The 118.Fn setgrent 119function 120is identical to 121.Fn setgroupent 122with an argument of zero. 123.Pp 124The 125.Fn endgrent 126function 127closes any open files. 128.Sh RETURN VALUES 129The functions 130.Fn getgrent , 131.Fn getgrnam , 132and 133.Fn getgrgid , 134return a pointer to the group entry if successful; if end-of-file 135is reached or an error occurs a null pointer is returned. 136The functions 137.Fn setgroupent 138and 139.Fn setgrent 140return the value 1 if successful, otherwise the value 1410 is returned. 142The functions 143.Fn endgrent 144and 145.Fn setgrfile 146have no return value. 147.Sh FILES 148.Bl -tag -width /etc/group -compact 149.It Pa /etc/group 150group database file 151.El 152.Sh SEE ALSO 153.Xr getpwent 3 , 154.Xr yp 4 , 155.Xr group 5 , 156.Xr nsswitch.conf 5 157.Sh HISTORY 158The functions 159.Fn endgrent , 160.Fn getgrent , 161.Fn getgrnam , 162.Fn getgrgid , 163and 164.Fn setgrent 165appeared in 166.At v7 . 167The functions 168.Fn setgrfile 169and 170.Fn setgroupent 171appeared in 172.Bx 4.3 Reno . 173.Sh COMPATIBILITY 174The historic function 175.Fn setgrfile , 176which allowed the specification of alternate password databases, has 177been deprecated and is no longer available. 178.Sh BUGS 179The functions 180.Fn getgrent , 181.Fn getgrnam , 182.Fn getgrgid , 183.Fn setgroupent 184and 185.Fn setgrent 186leave their results in an internal static object and return 187a pointer to that object. 188Subsequent calls to 189the same function 190will modify the same object. 191.Pp 192The functions 193.Fn getgrent , 194.Fn endgrent , 195.Fn setgroupent , 196and 197.Fn setgrent 198are fairly useless in a networked environment and should be 199avoided, if possible. 200.Fn getgrent 201makes no attempt to suppress duplicate information if multiple 202sources are specified in 203.Xr nsswitch.conf 5 . 204