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.\" $FreeBSD$ 30.\" 31.Dd December 1, 2017 32.Dt GETUID 2 33.Os 34.Sh NAME 35.Nm getuid , 36.Nm geteuid 37.Nd get user identification 38.Sh LIBRARY 39.Lb libc 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 49system call returns the real user ID of the calling process. 50The 51.Fn geteuid 52system call 53returns the effective user ID of the calling process. 54.Pp 55The real user ID is that of the user who has invoked the program. 56As the effective user ID 57gives the process additional permissions during 58execution of 59.Dq Em set-user-ID 60mode processes, 61.Fn getuid 62is used to determine the real-user-id of the calling process. 63.Sh ERRORS 64The 65.Fn getuid 66and 67.Fn geteuid 68system calls are always successful, and no return value is reserved to 69indicate an error. 70.Sh SEE ALSO 71.Xr getgid 2 , 72.Xr issetugid 2 , 73.Xr setgid 2 , 74.Xr setreuid 2 , 75.Xr setuid 2 76.Sh STANDARDS 77The 78.Fn geteuid 79and 80.Fn getuid 81system calls are expected to conform to 82.St -p1003.1-90 . 83.Sh HISTORY 84The 85.Fn getuid 86function appeared in 87.At v1 . 88The 89.Fn geteuid 90function appeared in 91.At v4 . 92