1.\" Copyright (c) 1983, 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. 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.\" @(#)setuid.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/setuid.2,v 1.13.2.7 2003/02/14 00:49:42 keramida Exp $ 34.\" $DragonFly: src/lib/libc/sys/setuid.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd June 4, 1993 37.Dt SETUID 2 38.Os 39.Sh NAME 40.Nm setuid , 41.Nm seteuid , 42.Nm setgid , 43.Nm setegid , 44.Nd set user and group ID 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In sys/types.h 49.In unistd.h 50.Ft int 51.Fn setuid "uid_t uid" 52.Ft int 53.Fn seteuid "uid_t euid" 54.Ft int 55.Fn setgid "gid_t gid" 56.Ft int 57.Fn setegid "gid_t egid" 58.Sh DESCRIPTION 59The 60.Fn setuid 61function 62sets the real and effective 63user IDs and the saved set-user-ID of the current process 64to the specified value. 65.\" Comment out next block for !_POSIX_SAVED_IDS 66.\" The real user ID and the saved set-user-ID are changed only if the 67.\" effective user ID is that of the super user. 68.\" I.e. 69.\" .Fn setuid 70.\" function is equal to 71.\" .Fn seteuid 72.\" function if the effective user ID is not that of the super user. 73.\" End of block 74The 75.Fn setuid 76function is permitted if the specified ID is equal to the real user ID 77.\" Comment out next line for !_POSIX_SAVED_IDS 78.\" or the saved set-user-ID 79.\" Next line is for Appendix B.4.2.2 case. 80or the effective user ID 81of the process, or if the effective user ID is that of the super user. 82.Pp 83The 84.Fn setgid 85function 86sets the real and effective 87group IDs and the saved set-group-ID of the current process 88to the specified value. 89.\" Comment out next block for !_POSIX_SAVED_IDS 90.\" The real group ID and the saved set-group-ID are changed only if the 91.\" effective user ID is that of the super user. 92.\" I.e. 93.\" .Fn setgid 94.\" function is equal to 95.\" .Fn setegid 96.\" function if the effective user ID is not that of the super user. 97.\" End of block 98The 99.Fn setgid 100function is permitted if the specified ID is equal to the real group ID 101.\" Comment out next line for !_POSIX_SAVED_IDS 102.\" or the saved set-group-ID 103.\" Next line is for Appendix B.4.2.2 case. 104or the effective group ID 105of the process, or if the effective user ID is that of the super user. 106.Pp 107The 108.Fn seteuid 109function 110.Pq Fn setegid 111sets the effective user ID (group ID) of the 112current process. 113The effective user ID may be set to the value 114of the real user ID or the saved set-user-ID (see 115.Xr intro 2 116and 117.Xr execve 2 ) ; 118in this way, the effective user ID of a set-user-ID executable 119may be toggled by switching to the real user ID, then re-enabled 120by reverting to the set-user-ID value. 121Similarly, the effective group ID may be set to the value 122of the real group ID or the saved set-group-ID. 123.Sh RETURN VALUES 124.Rv -std 125.Sh ERRORS 126The functions will fail if: 127.Bl -tag -width Er 128.It Bq Er EPERM 129The user is not the super user and the ID 130specified is not the real, effective ID, or saved ID. 131.El 132.Sh SEE ALSO 133.Xr getgid 2 , 134.Xr getuid 2 , 135.Xr issetugid 2 , 136.Xr setregid 2 , 137.Xr setreuid 2 138.Sh STANDARDS 139The 140.Fn setuid 141and 142.Fn setgid 143functions are compliant with the 144.St -p1003.1-90 145specification with 146.Li _POSIX_SAVED_IDS 147.\" Uncomment next line for !_POSIX_SAVED_IDS 148not 149defined with the permitted extensions from Appendix B.4.2.2. 150The 151.Fn seteuid 152and 153.Fn setegid 154functions are extensions based on the 155.Tn POSIX 156concept of 157.Li _POSIX_SAVED_IDS , 158and have been proposed for a future revision of the standard. 159.Sh HISTORY 160A 161.Fn setuid 162and a 163.Fn setgid 164function calls appeared in 165.At v7 . 166