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SETUID(2)		  FreeBSD System Calls Manual		     SETUID(2)

NAME
     setuid, seteuid, setgid, setegid -- set user and group ID

SYNOPSIS
     #include <unistd.h>

     int
     setuid(uid_t uid);

     int
     seteuid(uid_t euid);

     int
     setgid(gid_t gid);

     int
     setegid(gid_t egid);

DESCRIPTION
     The setuid() 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 effective user ID is that of the superuser,
     or	if the specified user ID is the	same as	the effective user ID.	If
     not, but the specified user ID is the same	as the real user ID, setuid()
     will set the effective user ID to the real	user ID.

     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 effective user ID is that of the superuser,
     or	if the specified group ID is the same as the effective group ID.  If
     not, but the specified group ID is	the same as the	real group ID,
     setgid() will set the effective group ID to the real group	ID.  Supple-
     mentary group IDs remain unchanged.

     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
     The setuid(), seteuid(), setgid(),	and setegid() functions	return the
     value 0 if	successful; otherwise the value	-1 is returned and the global
     variable errno is set to indicate the error.

ERRORS
     setuid() and seteuid() will succeed unless:

     [EPERM]		The user is not	the superuser and the requested	uid or
			euid is	not the	process's real,	effective, or saved
			UID.

     setgid() and setegid() will succeed unless:

     [EPERM]		The user is not	the superuser and the requested	gid or
			egid is	not the	process's real,	effective, or saved
			GID.

SEE ALSO
     getgid(2),	getuid(2), issetugid(2), setgroups(2), setregid(2),
     setresgid(2), setresuid(2), setreuid(2)

STANDARDS
     The setuid(), seteuid(), setgid(),	and setegid() functions	conform	to
     IEEE Std 1003.1-2008 ("POSIX.1").

HISTORY
     The setuid() system call first appeared in	Version	1 AT&T UNIX; setgid()
     in	Version	4 AT&T UNIX; and seteuid() and setegid() in 4.2BSD.

FreeBSD	13.0		       September 9, 2014		  FreeBSD 13.0
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY

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