NAME
seteuid, setegid - set effective user or group ID
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
int seteuid(uid_t euid);
int setegid(gid_t egid);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
seteuid(), setegid(): _BSD_SOURCE || _POSIX_C_SOURCE >= 200112L ||
_XOPEN_SOURCE >= 600
DESCRIPTION
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 setegid() with "group" instead of "user".
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
ERRORS
EPERM The calling process is not privileged (Linux: does not have the
CAP_SETUID capability in the case of seteuid(), or the
CAP_SETGID capability in the case of setegid()) and euid
(respectively, egid) is not the real user (group) ID, the
effective user (group) ID, or the saved set-user-ID (saved set-
group-ID).
CONFORMING TO
4.3BSD, POSIX.1-2001.
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 _POSIX_SAVED_IDS.
Under libc4, libc5 and glibc 2.0 seteuid(euid) is equivalent to
setreuid(-1, euid) and hence may change the saved set-user-ID. Under
glibc 2.1 and later it is equivalent to setresuid(-1, euid, -1) and
hence does not change the saved set-user-ID. Similar remarks hold for
setegid().
According to POSIX.1, seteuid() (setegid()) need not permit euid (egid)
to be the same value as the current effective user (group) ID, and some
implementations do not permit this.
SEE ALSO
geteuid(2), setresuid(2), setreuid(2), setuid(2), capabilities(7),
credentials(7)
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.