1.\" Copyright (c) 1980, 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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)getuid.2 8.1 (Berkeley) 6/4/93 29.\" 30.Dd December 1, 2017 31.Dt GETUID 2 32.Os 33.Sh NAME 34.Nm getuid , 35.Nm geteuid 36.Nd get user identification 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft uid_t 42.Fn getuid void 43.Ft uid_t 44.Fn geteuid void 45.Sh DESCRIPTION 46The 47.Fn getuid 48system call returns the real user ID of the calling process. 49The 50.Fn geteuid 51system call 52returns 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 67system calls are always successful, and no return value is reserved to 68indicate an error. 69.Sh SEE ALSO 70.Xr getgid 2 , 71.Xr issetugid 2 , 72.Xr setgid 2 , 73.Xr setreuid 2 , 74.Xr setuid 2 75.Sh STANDARDS 76The 77.Fn geteuid 78and 79.Fn getuid 80system calls are expected to conform to 81.St -p1003.1-90 . 82.Sh HISTORY 83The 84.Fn getuid 85function appeared in 86.At v1 . 87The 88.Fn geteuid 89function appeared in 90.At v4 . 91