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.\" $DragonFly: src/lib/libc/sys/setreuid.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd February 8, 2001 37.Dt SETREUID 2 38.Os 39.Sh NAME 40.Nm setreuid 41.Nd set real and effective user ID's 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft int 47.Fn setreuid "uid_t ruid" "uid_t euid" 48.Sh DESCRIPTION 49The real and effective user IDs of the 50current process are set according to the arguments. 51If 52.Fa ruid 53or 54.Fa euid 55is -1, the current uid is filled in by the system. 56Unprivileged users may change the real user 57ID to the effective user ID and vice-versa; only the super-user may 58make other changes. 59.Pp 60The 61.Fn setreuid 62function has been used to swap the real and effective user IDs 63in set-user-ID programs to temporarily relinquish the set-user-ID value. 64This purpose is now better served by the use of the 65.Fn seteuid 66function (see 67.Xr setuid 2 ) . 68.Pp 69When setting the real and effective user IDs to the same value, 70the standard 71.Fn setuid 72function is preferred. 73.Sh RETURN VALUES 74.Rv -std setreuid 75.Sh ERRORS 76.Bl -tag -width Er 77.It Bq Er EPERM 78The current process is not the super-user and a change 79other than changing the effective user-id to the real user-id 80was specified. 81.El 82.Sh SEE ALSO 83.Xr getuid 2 , 84.Xr issetugid 2 , 85.Xr seteuid 2 , 86.Xr setuid 2 87.Sh HISTORY 88The 89.Fn setreuid 90system call appeared in 91.Bx 4.2 . 92