1.\" $OpenBSD: getgid.2,v 1.19 2015/09/10 17:55:21 schwarze Exp $ 2.\" $NetBSD: getgid.2,v 1.5 1995/02/27 12:32:53 cgd Exp $ 3.\" 4.\" Copyright (c) 1983, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)getgid.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: September 10 2015 $ 34.Dt GETGID 2 35.Os 36.Sh NAME 37.Nm getgid , 38.Nm getegid 39.Nd get group process identification 40.Sh SYNOPSIS 41.In unistd.h 42.Ft gid_t 43.Fn getgid void 44.Ft gid_t 45.Fn getegid void 46.Sh DESCRIPTION 47The 48.Fn getgid 49function returns the real group ID of the calling process and the 50.Fn getegid 51function returns the effective group ID of the calling process. 52.Pp 53The real group ID is specified at login time. 54.Pp 55The real group ID is the group of the user who invoked the program. 56As the effective group ID gives the process additional permissions 57during the execution of 58.Dq Em set-group-ID 59mode processes, 60.Fn getgid 61is used to determine the real group ID of the calling process. 62.Sh ERRORS 63The 64.Fn getgid 65and 66.Fn getegid 67functions are always successful, and no return value is reserved to 68indicate an error. 69.Sh SEE ALSO 70.Xr getgroups 2 , 71.Xr getresgid 2 , 72.Xr getuid 2 , 73.Xr setgid 2 , 74.Xr setregid 2 75.Sh STANDARDS 76The 77.Fn getgid 78and 79.Fn getegid 80functions conform to 81.St -p1003.1-2008 . 82.Sh HISTORY 83The 84.Fn getgid 85system call first appeared in 86.At v4 , 87and 88.Fn getegid 89in 90.At v7 . 91