DragonFly On-Line Manual Pages
SETUID(2) DragonFly System Calls Manual SETUID(2)
setuid, seteuid, setgid, setegid -- set user and group ID
Standard C Library (libc, -lc)
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 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.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
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.
getgid(2), getuid(2), issetugid(2), setregid(2), setreuid(2)
The setuid() and setgid() functions are compliant with the ISO/IEC
9945-1:1990 (``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
A setuid() and a setgid() function calls appeared in Version 7 AT&T UNIX.
DragonFly 5.3 June 4, 1993 DragonFly 5.3