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.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt SETUID 2 37.Os 38.Sh NAME 39.Nm setuid , 40.Nm seteuid , 41.Nm setgid , 42.Nm setegid , 43.Nd set user and group ID 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.Fd #include <sys/types.h> 48.Fd #include <unistd.h> 49.Ft int 50.Fn setuid "uid_t uid" 51.Ft int 52.Fn seteuid "uid_t euid" 53.Ft int 54.Fn setgid "gid_t gid" 55.Ft int 56.Fn setegid "gid_t egid" 57.Sh DESCRIPTION 58The 59.Fn setuid 60function 61sets the real and effective 62user IDs and the saved set-user-ID of the current process 63to the specified value. 64.\" Comment out next block for !_POSIX_SAVED_IDS 65.\" The real user ID and the saved set-user-ID are changed only if the 66.\" effective user ID is that of the super user. 67.\" I.e. 68.\" .Fn setuid 69.\" function is equal to 70.\" .Fn seteuid 71.\" function if the effective user ID is not that of the super user. 72.\" End of block 73The 74.Fn setuid 75function is permitted if the specified ID is equal to the real user ID 76.\" Comment out next line for !_POSIX_SAVED_IDS 77.\" or the saved set-user-ID 78.\" Next line is for Appendix B.4.2.2 case. 79or the effective user ID 80of the process, or if the effective user ID is that of the super user. 81.Pp 82The 83.Fn setgid 84function 85sets the real and effective 86group IDs and the saved set-group-ID of the current process 87to the specified value. 88.\" Comment out next block for !_POSIX_SAVED_IDS 89.\" The real group ID and the saved set-group-ID are changed only if the 90.\" effective user ID is that of the super user. 91.\" I.e. 92.\" .Fn setgid 93.\" function is equal to 94.\" .Fn setegid 95.\" function if the effective user ID is not that of the super user. 96.\" End of block 97The 98.Fn setgid 99function is permitted if the specified ID is equal to the real group ID 100.\" Comment out next line for !_POSIX_SAVED_IDS 101.\" or the saved set-group-ID 102.\" Next line is for Appendix B.4.2.2 case. 103or the effective group ID 104of the process, or if the effective user ID is that of the super user. 105.Pp 106The 107.Fn seteuid 108function 109.Pq Fn setegid 110sets the effective user ID (group ID) of the 111current process. 112The effective user ID may be set to the value 113of the real user ID or the saved set-user-ID (see 114.Xr intro 2 115and 116.Xr execve 2 ) ; 117in this way, the effective user ID of a set-user-ID executable 118may be toggled by switching to the real user ID, then re-enabled 119by reverting to the set-user-ID value. 120Similarly, the effective group ID may be set to the value 121of the real group ID or the saved set-user-ID. 122.Sh RETURN VALUES 123Upon success, these functions return 0; 124otherwise \-1 is returned. 125.Pp 126If the user is not the super user, or the uid 127specified is not the real, effective ID, or saved ID, 128these functions return \-1. 129.Sh SEE ALSO 130.Xr getgid 2 , 131.Xr getuid 2 , 132.Xr issetugid 2 , 133.Xr setregid 2 , 134.Xr setreuid 2 135.Sh STANDARDS 136The 137.Fn setuid 138and 139.Fn setgid 140functions are compliant with the 141.St -p1003.1-90 142specification with 143.Li _POSIX_SAVED_IDS 144.\" Uncomment next line for !_POSIX_SAVED_IDS 145not 146defined with the permitted extensions from Appendix B.4.2.2. 147The 148.Fn seteuid 149and 150.Fn setegid 151functions are extensions based on the 152.Tn POSIX 153concept of 154.Li _POSIX_SAVED_IDS , 155and have been proposed for a future revision of the standard. 156.Sh HISTORY 157A 158.Fn setuid 159and a 160.Fn setgid 161function calls appeared in 162.At v7 . 163