1.\" $NetBSD: getgrent.3,v 1.16 2002/04/29 01:41:44 simonb 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 \*[Lt]grp.h\*[Gt] 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 void 63.Fn setgrent void 64.Ft void 65.Fn endgrent void 66.Sh DESCRIPTION 67These functions operate on the group database file which is described in 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 functions 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 equivalent to 118.Fn setgroupent 119with an argument of zero. 120.Pp 121The 122.Fn endgrent 123function 124closes any open files. 125.Sh RETURN VALUES 126The functions 127.Fn getgrent , 128.Fn getgrnam , 129and 130.Fn getgrgid , 131return a pointer to the group entry if successful; if end-of-file 132is reached or an error occurs a null pointer is returned. 133The 134.Fn setgroupent 135function returns the value 1 if successful, otherwise the value 1360 is returned. 137The 138.Fn endgrent 139and 140.Fn setgrent 141functions have no return value. 142.Sh FILES 143.Bl -tag -width /etc/group -compact 144.It Pa /etc/group 145group database file 146.El 147.Sh SEE ALSO 148.Xr getpwent 3 , 149.Xr group 5 , 150.Xr nsswitch.conf 5 151.Sh STANDARDS 152The 153.Fn getgrnam 154and 155.Fn getgrgid 156functions conform to 157.St -p1003.1-90 . 158.Sh HISTORY 159The functions 160.Fn endgrent , 161.Fn getgrent , 162.Fn getgrnam , 163.Fn getgrgid , 164and 165.Fn setgrent 166appeared in 167.At v7 . 168The functions 169.Fn setgrfile 170and 171.Fn setgroupent 172appeared in 173.Bx 4.3 Reno . 174.Sh COMPATIBILITY 175The historic function 176.Fn setgrfile , 177which allowed the specification of alternative password databases, has 178been deprecated and is no longer available. 179.Sh BUGS 180The functions 181.Fn getgrent , 182.Fn getgrnam , 183.Fn getgrgid , 184.Fn setgroupent 185and 186.Fn setgrent 187leave their results in an internal static object and return 188a pointer to that object. Subsequent 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