NAME
setuid, seteuid,
setgid, setegid —
set user and group ID
LIBRARY
library “libc”
SYNOPSIS
#include
<sys/types.h>
#include <unistd.h>
int
setuid(uid_t
uid);
int
seteuid(uid_t
euid);
int
setgid(gid_t
gid);
int
setegid(gid_t
egid);
DESCRIPTION
Thesetuid()
function sets the real and effective user IDs and the saved set-user-ID of the
current process to the specified value. The setuid()
function is permitted if the specified ID is equal to the real user ID or the
effective user ID of the process, or if the effective user ID is that of the
super user.
The
setgid()
function sets the real and effective group IDs and the saved set-group-ID of
the current process to the specified value. The
setgid() function is permitted if the specified ID
is equal to the real group ID or the effective group ID of the process, or
if the effective user ID is that of the super user.
The
seteuid()
function
(setegid())
sets the effective user ID (group ID) of the current process. The effective
user ID may be set to the value of the real user ID or the saved set-user-ID
(see intro(2) and
execve(2)); in this way, the effective user ID of a set-user-ID
executable may be toggled by switching to the real user ID, then re-enabled
by reverting to the set-user-ID value. Similarly, the effective group ID may
be set to the value of the real group ID or the saved set-group-ID.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORS
The functions will fail if:
- [
EPERM] - The user is not the super user and the ID specified is not the real, effective ID, or saved ID.
SEE ALSO
getgid(2), getuid(2), issetugid(2), setregid(2), setreuid(2)
STANDARDS
The setuid() and
setgid() functions are compliant with the
IEEE Std 1003.1-1990 (“POSIX.1”)
specification with _POSIX_SAVED_IDS not defined with
the permitted extensions from Appendix B.4.2.2. The
seteuid() and setegid()
functions are extensions based on the POSIX concept of
_POSIX_SAVED_IDS, and have been proposed for a
future revision of the standard.
HISTORY
A setuid() and a
setgid() function calls appeared in
Version 7 AT&T UNIX.