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. 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.\" @(#)setreuid.2 8.2 (Berkeley) 4/16/94 29.\" 30.Dd February 8, 2001 31.Dt SETREUID 2 32.Os 33.Sh NAME 34.Nm setreuid 35.Nd set real and effective user ID's 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft int 41.Fn setreuid "uid_t ruid" "uid_t euid" 42.Sh DESCRIPTION 43The real and effective user IDs of the 44current process are set according to the arguments. 45If 46.Fa ruid 47or 48.Fa euid 49is -1, the current uid is filled in by the system. 50Unprivileged users may change the real user 51ID to the effective user ID and vice-versa; only the super-user may 52make other changes. 53.Pp 54If the real user ID is changed (i.e.\& 55.Fa ruid 56is not -1) or the effective user ID is changed to something other than 57the real user ID, then the saved user ID will be set to the effective user ID. 58.Pp 59The 60.Fn setreuid 61system call 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.Xr seteuid 2 65system call. 66.Pp 67When setting the real and effective user IDs to the same value, 68the standard 69.Fn setuid 70system call is preferred. 71.Sh RETURN VALUES 72.Rv -std setreuid 73.Sh ERRORS 74.Bl -tag -width Er 75.It Bq Er EPERM 76The current process is not the super-user and a change 77other than changing the effective user-id to the real user-id 78was specified. 79.El 80.Sh SEE ALSO 81.Xr getuid 2 , 82.Xr issetugid 2 , 83.Xr seteuid 2 , 84.Xr setuid 2 85.Sh HISTORY 86The 87.Fn setreuid 88system call appeared in 89.Bx 4.2 . 90