1.\" $NetBSD: getgrent.3,v 1.14 2001/09/16 02:30:24 wiz 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 25, 1999 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 LIBRARY 49.Lb libc 50.Sh SYNOPSIS 51.Fd #include <sys/types.h> 52.Fd #include <grp.h> 53.Ft struct group * 54.Fn getgrent void 55.Ft struct group * 56.Fn getgrnam "const char *name" 57.Ft struct group * 58.Fn getgrgid "gid_t gid" 59.Ft int 60.Fn setgroupent "int stayopen" 61.\" .Ft void 62.\" .Fn setgrfile "const char *name" 63.Ft void 64.Fn setgrent void 65.Ft void 66.Fn endgrent void 67.Sh DESCRIPTION 68These functions operate on the group database file which is described in 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 gid_t 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 functions 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 equivalent to 119.Fn setgroupent 120with an argument of zero. 121.Pp 122The 123.Fn endgrent 124function 125closes any open files. 126.Sh RETURN VALUES 127The functions 128.Fn getgrent , 129.Fn getgrnam , 130and 131.Fn getgrgid , 132return a pointer to the group entry if successful; if end-of-file 133is reached or an error occurs a null pointer is returned. 134The 135.Fn setgroupent 136function returns the value 1 if successful, otherwise the value 1370 is returned. 138The 139.Fn endgrent 140and 141.Fn setgrent 142functions have no return value. 143.Sh FILES 144.Bl -tag -width /etc/group -compact 145.It Pa /etc/group 146group database file 147.El 148.Sh SEE ALSO 149.Xr getpwent 3 , 150.Xr group 5 , 151.Xr nsswitch.conf 5 152.Sh STANDARDS 153The 154.Fn getgrnam 155and 156.Fn getgrgid 157functions conform to 158.St -p1003.1-90 . 159.Sh HISTORY 160The functions 161.Fn endgrent , 162.Fn getgrent , 163.Fn getgrnam , 164.Fn getgrgid , 165and 166.Fn setgrent 167appeared in 168.At v7 . 169The functions 170.Fn setgrfile 171and 172.Fn setgroupent 173appeared in 174.Bx 4.3 Reno . 175.Sh COMPATIBILITY 176The historic function 177.Fn setgrfile , 178which allowed the specification of alternative password databases, has 179been deprecated and is no longer available. 180.Sh BUGS 181The functions 182.Fn getgrent , 183.Fn getgrnam , 184.Fn getgrgid , 185.Fn setgroupent 186and 187.Fn setgrent 188leave their results in an internal static object and return 189a pointer to that object. Subsequent calls to 190the same function 191will modify the same object. 192.Pp 193The functions 194.Fn getgrent , 195.Fn endgrent , 196.Fn setgroupent , 197and 198.Fn setgrent 199are fairly useless in a networked environment and should be 200avoided, if possible. 201.Fn getgrent 202makes no attempt to suppress duplicate information if multiple 203sources are specified in 204.Xr nsswitch.conf 5 205