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: getgrent.3,v 1.9 1997/02/22 14:58:07 peter Exp $ 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 <sys/types.h> 49.Fd #include <grp.h> 50.Ft struct group * 51.Fn getgrent void 52.Ft struct group * 53.Fn getgrnam "const char *name" 54.Ft struct group * 55.Fn getgrgid "gid_t gid" 56.Ft int 57.Fn setgroupent "int stayopen" 58.\" .Ft void 59.\" .Fn setgrfile "const char *name" 60.Ft int 61.Fn setgrent void 62.Ft void 63.Fn endgrent void 64.Sh DESCRIPTION 65These functions operate on the group database file 66.Pa /etc/group 67which is described 68in 69.Xr group 5 . 70Each line of the database is defined by the structure 71.Ar group 72found in the include 73file 74.Aq Pa grp.h : 75.Bd -literal -offset indent 76struct group { 77 char *gr_name; /* group name */ 78 char *gr_passwd; /* group password */ 79 int gr_gid; /* group id */ 80 char **gr_mem; /* group members */ 81}; 82.Ed 83.Pp 84The functions 85.Fn getgrnam 86and 87.Fn getgrgid 88search the group database for the given group name pointed to by 89.Ar name 90or the group id pointed to by 91.Ar gid , 92respectively, returning the first one encountered. Identical group 93names or group gids may result in undefined behavior. 94.Pp 95The 96.Fn getgrent 97function 98sequentially reads the group database and is intended for programs 99that wish to step through the complete list of groups. 100.Pp 101All three routines will open the group file for reading, if necessary. 102.Pp 103The 104.Fn setgroupent 105function 106opens the file, or rewinds it if it is already open. If 107.Fa stayopen 108is non-zero, file descriptors are left open, significantly speeding 109functions subsequent calls. This functionality is unnecessary for 110.Fn getgrent 111as it doesn't close its file descriptors by default. It should also 112be noted that it is dangerous for long-running programs to use this 113functionality as the group file may be updated. 114.Pp 115The 116.Fn setgrent 117function 118is identical to 119.Fn setgroupent 120with an argument of zero. 121.Pp 122The 123.Fn endgrent 124function 125closes any open files. 126.Sh YP/NIS INTERACTION 127When the 128.Xr yp 4 129group database is enabled, the 130.Fn getgrnam 131and 132.Fn getgrgid 133functions use the YP maps 134.Dq Li group.byname 135and 136.Dq Li group.bygid , 137respectively, if the requested group is not found in the local 138.Pa /etc/group 139file. The 140.Fn getgrent 141function will step through the YP map 142.Dq Li group.byname 143if the entire map is enabled as described in 144.Xr group 5 . 145.Sh RETURN VALUES 146The functions 147.Fn getgrent , 148.Fn getgrnam , 149and 150.Fn getgrgid , 151return a pointer to the group entry if successful; if end-of-file 152is reached or an error occurs a null pointer is returned. 153The functions 154.Fn setgroupent 155and 156.Fn setgrent 157return the value 1 if successful, otherwise the value 1580 is returned. 159The functions 160.Fn endgrent 161and 162.Fn setgrfile 163have no return value. 164.Sh FILES 165.Bl -tag -width /etc/group -compact 166.It Pa /etc/group 167group database file 168.El 169.Sh SEE ALSO 170.Xr getpwent 3 , 171.Xr yp 4 , 172.Xr group 5 173.Sh HISTORY 174The functions 175.Fn endgrent , 176.Fn getgrent , 177.Fn getgrnam , 178.Fn getgrgid , 179and 180.Fn setgrent 181appeared in 182.At v7 . 183The functions 184.Fn setgrfile 185and 186.Fn setgroupent 187appeared in 188.Bx 4.3 Reno . 189.Sh COMPATIBILITY 190The historic function 191.Fn setgrfile , 192which allowed the specification of alternate password databases, has 193been deprecated and is no longer available. 194.Sh BUGS 195The functions 196.Fn getgrent , 197.Fn getgrnam , 198.Fn getgrgid , 199.Fn setgroupent 200and 201.Fn setgrent 202leave their results in an internal static object and return 203a pointer to that object. Subsequent calls to 204the same function 205will modify the same object. 206