1.\" $NetBSD: getgrent.3,v 1.8 1995/02/27 04:12:36 cgd Exp $ 2.\" 3.\" Copyright (c) 1989, 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. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)getgrent.3 8.2 (Berkeley) 4/19/94 35.\" 36.Dd April 19, 1994 37.Dt GETGRENT 3 38.Os 39.Sh NAME 40.Nm getgrent , 41.Nm getgrnam , 42.Nm getgrgid , 43.Nm setgroupent , 44.\" .Nm setgrfile , 45.Nm setgrent , 46.Nm endgrent 47.Nd group database operations 48.Sh SYNOPSIS 49.Fd #include <sys/types.h> 50.Fd #include <grp.h> 51.Ft struct group * 52.Fn getgrent void 53.Ft struct group * 54.Fn getgrnam "const char *name" 55.Ft struct group * 56.Fn getgrgid "gid_t gid" 57.Ft int 58.Fn setgroupent "int stayopen" 59.\" .Ft void 60.\" .Fn setgrfile "const char *name" 61.Ft void 62.Fn setgrent void 63.Ft void 64.Fn endgrent void 65.Sh DESCRIPTION 66These functions operate on the group database file 67.Pa /etc/group 68which is described 69in 70.Xr group 5 . 71Each line of the database is defined by the structure 72.Ar group 73found in the include 74file 75.Aq Pa grp.h : 76.Bd -literal -offset indent 77struct group { 78 char *gr_name; /* group name */ 79 char *gr_passwd; /* group password */ 80 gid_t gr_gid; /* group id */ 81 char **gr_mem; /* group members */ 82}; 83.Ed 84.Pp 85The functions 86.Fn getgrnam 87and 88.Fn getgrgid 89search the group database for the given group name pointed to by 90.Ar name 91or the group id pointed to by 92.Ar gid , 93respectively, returning the first one encountered. Identical group 94names or group gids may result in undefined behavior. 95.Pp 96The 97.Fn getgrent 98function 99sequentially reads the group database and is intended for programs 100that wish to step through the complete list of groups. 101.Pp 102All three routines will open the group file for reading, if necessary. 103.Pp 104The 105.Fn setgroupent 106function 107opens the file, or rewinds it if it is already open. If 108.Fa stayopen 109is non-zero, file descriptors are left open, significantly speeding 110functions subsequent calls. This functionality is unnecessary for 111.Fn getgrent 112as it doesn't close its file descriptors by default. It should also 113be noted that it is dangerous for long-running programs to use this 114functionality as the group file may be updated. 115.Pp 116The 117.Fn setgrent 118function 119is equivalent to 120.Fn setgroupent 121with an argument of zero. 122.Pp 123The 124.Fn endgrent 125function 126closes any open files. 127.Sh RETURN VALUES 128The functions 129.Fn getgrent , 130.Fn getgrnam , 131and 132.Fn getgrgid , 133return a pointer to the group entry if successful; if end-of-file 134is reached or an error occurs a null pointer is returned. 135The 136.Fn setgroupent 137function returns the value 1 if successful, otherwise the value 1380 is returned. 139The 140.Fn endgrent 141and 142.Fn setgrent 143functions have no return value. 144.Sh FILES 145.Bl -tag -width /etc/group -compact 146.It Pa /etc/group 147group database file 148.El 149.Sh SEE ALSO 150.Xr getpwent 3 , 151.Xr group 5 152.Sh HISTORY 153The functions 154.Fn endgrent , 155.Fn getgrent , 156.Fn getgrnam , 157.Fn getgrgid , 158and 159.Fn setgrent 160appeared in 161.At v7 . 162The functions 163.Fn setgrfile 164and 165.Fn setgroupent 166appeared in 167.Bx 4.3 Reno . 168.Sh COMPATIBILITY 169The historic function 170.Fn setgrfile , 171which allowed the specification of alternate password databases, has 172been deprecated and is no longer available. 173.Sh BUGS 174The functions 175.Fn getgrent , 176.Fn getgrnam , 177.Fn getgrgid , 178.Fn setgroupent 179and 180.Fn setgrent 181leave their results in an internal static object and return 182a pointer to that object. Subsequent calls to 183the same function 184will modify the same object. 185.Pp 186The functions 187.Fn getgrent , 188.Fn endgrent , 189.Fn setgroupent , 190and 191.Fn setgrent 192are fairly useless in a networked environment and should be 193avoided, if possible. 194