1.\" Copyright (c) 1980, 1991, 1993, 1994 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. 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.\" @(#)setreuid.2 8.2 (Berkeley) 4/16/94 33.\" $FreeBSD: src/lib/libc/sys/setreuid.2,v 1.6.2.6 2001/12/14 18:34:01 ru Exp $ 34.\" 35.Dd February 8, 2001 36.Dt SETREUID 2 37.Os 38.Sh NAME 39.Nm setreuid 40.Nd set real and effective user IDs 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In unistd.h 45.Ft int 46.Fn setreuid "uid_t ruid" "uid_t euid" 47.Sh DESCRIPTION 48The real and effective user IDs of the 49current process are set according to the arguments. 50If 51.Fa ruid 52or 53.Fa euid 54is -1, the current uid is filled in by the system. 55Unprivileged users may change the real user 56ID to the effective user ID and vice-versa; only the super-user may 57make other changes. 58.Pp 59The 60.Fn setreuid 61function has been used to swap the real and effective user IDs 62in set-user-ID programs to temporarily relinquish the set-user-ID value. 63This purpose is now better served by the use of the 64.Fn seteuid 65function (see 66.Xr setuid 2 ) . 67.Pp 68When setting the real and effective user IDs to the same value, 69the standard 70.Fn setuid 71function is preferred. 72.Sh RETURN VALUES 73.Rv -std setreuid 74.Sh ERRORS 75.Bl -tag -width Er 76.It Bq Er EPERM 77The current process is not the super-user and a change 78other than changing the effective user-id to the real user-id 79was specified. 80.El 81.Sh SEE ALSO 82.Xr getuid 2 , 83.Xr issetugid 2 , 84.Xr seteuid 2 , 85.Xr setuid 2 86.Sh HISTORY 87The 88.Fn setreuid 89system call appeared in 90.Bx 4.2 . 91