1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" 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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)getuid.2 6.4 (Berkeley) 3/10/91 33.\" 34.Dd March 10, 1991 35.Dt GETUID 2 36.Os BSD 4 37.Sh NAME 38.Nm getuid , 39.Nm geteuid 40.Nd get user identification 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Fd #include <sys/types.h> 44.Ft uid_t 45.Fn getuid void 46.Ft uid_t 47.Fn geteuid void 48.Sh DESCRIPTION 49The 50.Fn getuid 51function returns the real user ID of the calling process. 52The 53.Fn geteuid 54function 55returns the effective user ID of the calling process. 56.Pp 57The real user ID is that of the user who has invoked the program. 58As the effective user ID 59gives the process additional permissions during 60execution of 61.Dq Em set-user-ID 62mode processes, 63.Fn getuid 64is used to determine the real-user-id of the calling process. 65.Sh ERRORS 66The 67.Fn getuid 68and 69.Fn geteuid 70functions are always successful, and no return value is reserved to 71indicate an error. 72.Sh SEE ALSO 73.Xr getgid 2 , 74.Xr setreuid 2 75.Sh STANDARDS 76.Fn Geteuid 77and 78.Fn getuid 79conform to IEEE Std 1003.1-1988 80.Pq Dq Tn POSIX . 81