1.\" Copyright (c) 1989, 1991 The Regents of the University of California. 2.\" 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 6.8 (Berkeley) 4/20/91 33.\" $Id: getgrent.3,v 1.7 1994/01/10 23:32:28 jtc Exp $ 34.\" 35.Dd April 20, 1991 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 void 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 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 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 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.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