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.Dd December 1, 2017 29.Dt GETUID 2 30.Os 31.Sh NAME 32.Nm getuid , 33.Nm geteuid 34.Nd get user identification 35.Sh LIBRARY 36.Lb libc 37.Sh SYNOPSIS 38.In unistd.h 39.Ft uid_t 40.Fn getuid void 41.Ft uid_t 42.Fn geteuid void 43.Sh DESCRIPTION 44The 45.Fn getuid 46system call returns the real user ID of the calling process. 47The 48.Fn geteuid 49system call 50returns the effective user ID of the calling process. 51.Pp 52The real user ID is that of the user who has invoked the program. 53As the effective user ID 54gives the process additional permissions during 55execution of 56.Dq Em set-user-ID 57mode processes, 58.Fn getuid 59is used to determine the real-user-id of the calling process. 60.Sh ERRORS 61The 62.Fn getuid 63and 64.Fn geteuid 65system calls are always successful, and no return value is reserved to 66indicate an error. 67.Sh SEE ALSO 68.Xr getgid 2 , 69.Xr issetugid 2 , 70.Xr setgid 2 , 71.Xr setreuid 2 , 72.Xr setuid 2 73.Sh STANDARDS 74The 75.Fn geteuid 76and 77.Fn getuid 78system calls are expected to conform to 79.St -p1003.1-90 . 80.Sh HISTORY 81The 82.Fn getuid 83function appeared in 84.At v1 . 85The 86.Fn geteuid 87function appeared in 88.At v4 . 89