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.\" @(#)getgrent.3 8.2 (Berkeley) 4/19/94 33.\" 34.Dd April 19, 1994 35.Dt GETGRENT 3 36.Os 37.Sh NAME 38.Nm getgrent , 39.Nm getgrnam , 40.Nm getgrgid , 41.Nm setgroupent , 42.\" .Nm setgrfile , 43.Nm setgrent , 44.Nm endgrent 45.Nd group database operations 46.Sh SYNOPSIS 47.Fd #include <grp.h> 48.Ft struct group * 49.Fn getgrent void 50.Ft struct group * 51.Fn getgrnam "const char *name" 52.Ft struct group * 53.Fn getgrgid "gid_t gid" 54.Ft struct group * 55.Fn setgroupent "int stayopen" 56.\" .Ft void 57.\" .Fn setgrfile "const char *name" 58.Ft int 59.Fn setgrent void 60.Ft void 61.Fn endgrent void 62.Sh DESCRIPTION 63These functions operate on the group database file 64.Pa /etc/group 65which is described 66in 67.Xr group 5 . 68Each line of the database is defined by the structure 69.Ar group 70found in the include 71file 72.Aq Pa grp.h : 73.Bd -literal -offset indent 74struct group { 75 char *gr_name; /* group name */ 76 char *gr_passwd; /* group password */ 77 gid_t gr_gid; /* group id */ 78 char **gr_mem; /* group members */ 79}; 80.Ed 81.Pp 82The functions 83.Fn getgrnam 84and 85.Fn getgrgid 86search the group database for the given group name pointed to by 87.Ar name 88or the group id pointed to by 89.Ar gid , 90respectively, returning the first one encountered. Identical group 91names or group gids may result in undefined behavior. 92.Pp 93The 94.Fn getgrent 95function 96sequentially reads the group database and is intended for programs 97that wish to step through the complete list of groups. 98.Pp 99All three routines will open the group file for reading, if necessary. 100.Pp 101The 102.Fn setgroupent 103function 104opens the file, or rewinds it if it is already open. If 105.Fa stayopen 106is non-zero, file descriptors are left open, significantly speeding 107functions subsequent calls. This functionality is unnecessary for 108.Fn getgrent 109as it doesn't close its file descriptors by default. It should also 110be noted that it is dangerous for long-running programs to use this 111functionality as the group file may be updated. 112.Pp 113The 114.Fn setgrent 115function 116is identical to 117.Fn setgroupent 118with an argument of zero. 119.Pp 120The 121.Fn endgrent 122function 123closes any open files. 124.Sh RETURN VALUES 125The functions 126.Fn getgrent , 127.Fn getgrnam , 128and 129.Fn getgrgid , 130return a pointer to the group entry if successful; if end-of-file 131is reached or an error occurs a null pointer is returned. 132The functions 133.Fn setgroupent 134and 135.Fn setgrent 136return the value 1 if successful, otherwise the value 1370 is returned. 138The functions 139.Fn endgrent 140and 141.Fn setgrfile 142have 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.Fn getpwent 3 , 150.Fn group 5 151.Sh HISTORY 152The functions 153.Fn endgrent , 154.Fn getgrent , 155.Fn getgrnam , 156.Fn getgrgid , 157and 158.Fn setgrent 159appeared in 160.At v7 . 161The functions 162.Fn setgrfile 163and 164.Fn setgroupent 165appeared in 166.Bx 4.3 Reno . 167.Sh COMPATIBILITY 168The historic function 169.Fn setgrfile , 170which allowed the specification of alternate password databases, has 171been deprecated and is no longer available. 172.Sh BUGS 173The functions 174.Fn getgrent , 175.Fn getgrnam , 176.Fn getgrgid , 177.Fn setgroupent 178and 179.Fn setgrent 180leave their results in an internal static object and return 181a pointer to that object. Subsequent calls to 182the same function 183will modify the same object. 184.Pp 185The functions 186.Fn getgrent , 187.Fn endgrent , 188.Fn setgroupent , 189and 190.Fn setgrent 191are fairly useless in a networked environment and should be 192avoided, if possible. 193