1.\" $OpenBSD: getuid.2,v 1.16 2015/09/10 17:55:21 schwarze Exp $ 2.\" $NetBSD: getuid.2,v 1.6 1995/02/27 12:33:37 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 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.\" @(#)getuid.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: September 10 2015 $ 34.Dt GETUID 2 35.Os 36.Sh NAME 37.Nm getuid , 38.Nm geteuid 39.Nd get user identification 40.Sh SYNOPSIS 41.In unistd.h 42.Ft uid_t 43.Fn getuid void 44.Ft uid_t 45.Fn geteuid void 46.Sh DESCRIPTION 47The 48.Fn getuid 49function returns the real user ID of the calling process. 50The 51.Fn geteuid 52function returns the effective user ID of the calling process. 53.Pp 54The real user ID is that of the user who has invoked the program. 55As the effective user ID 56gives the process additional permissions during 57execution of 58.Dq Em set-user-ID 59mode processes, 60.Fn getuid 61is used to determine the real user ID of the calling process. 62.Sh ERRORS 63The 64.Fn getuid 65and 66.Fn geteuid 67functions are always successful, and no return value is reserved to 68indicate an error. 69.Sh SEE ALSO 70.Xr getgid 2 , 71.Xr getresuid 2 , 72.Xr setreuid 2 , 73.Xr setuid 2 74.Sh STANDARDS 75The 76.Fn getuid 77and 78.Fn geteuid 79functions conform to 80.St -p1003.1-2008 . 81.Sh HISTORY 82The 83.Fn getuid 84system call first appeared in 85.At v1 , 86and 87.Fn geteuid 88in 89.At v7 . 90