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.\" Copyright (C) 2001 Andries Brouwer (aeb@cwi.nl)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" [should really be seteuid.3]
.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Added notes on capability requirements
.\"
.TH SETEUID 2 2009-10-17 "Linux" "Linux Programmer's Manual"
.SH NAME
seteuid, setegid \- set effective user or group ID
.SH SYNOPSIS
.B #include <sys/types.h>
.br
.B #include <unistd.h>
.sp
.BI "int seteuid(uid_t " euid );
.br
.BI "int setegid(gid_t " egid );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR seteuid (),
.BR setegid ():
.RS 4
_BSD_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600
.RE
.ad
.SH DESCRIPTION
.BR seteuid ()
sets the effective user ID of the calling process.
Unprivileged user processes may only set the effective user ID to the
real user ID, the effective user ID or the saved set-user-ID.
Precisely the same holds for
.BR setegid ()
with "group" instead of "user".
.\" When
.\" .I euid
.\" equals \-1, nothing is changed.
.\" (This is an artifact of the implementation in glibc of seteuid()
.\" using setresuid(2).)
.SH "RETURN VALUE"
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.\" .TP
.\" .B EINVAL
.TP
.B EPERM
The calling process is not privileged (Linux: does not have the
.B CAP_SETUID
capability in the case of
.BR seteuid (),
or the
.B CAP_SETGID
capability in the case of
.BR setegid ())
and
.I euid
(respectively,
.IR egid )
is not the real user (group) ID, the effective user (group) ID,
or the saved set-user-ID (saved set-group-ID).
.SH "CONFORMING TO"
4.3BSD, POSIX.1-2001.
.SH NOTES
Setting the effective user (group) ID to the
saved set-user-ID (saved set-group-ID) is
possible since Linux 1.1.37 (1.1.38).
On an arbitrary system one should check
.BR _POSIX_SAVED_IDS .
.LP
Under libc4, libc5 and glibc 2.0
.BI seteuid( euid )
is equivalent to
.BI setreuid(\-1, " euid" )
and hence may change the saved set-user-ID.
Under glibc 2.1 and later it is equivalent to
.BI setresuid(\-1, " euid" ", \-1)"
and hence does not change the saved set-user-ID.
Similar remarks hold for
.BR setegid ().
According to POSIX.1,
.BR seteuid ()
.RB ( setegid ())
need not permit
.I euid
.RI ( egid )
to be the same value as the current effective user (group) ID,
and some implementations do not permit this.
.SH "SEE ALSO"
.BR geteuid (2),
.BR setresuid (2),
.BR setreuid (2),
.BR setuid (2),
.BR capabilities (7),
.BR credentials (7)
.SH COLOPHON
This page is part of release 3.27 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
|
