bsd man page for setuid

SETUID(3)						     Library Functions Manual							 SETUID(3)

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

SYNOPSIS
       #include <sys/types.h>

       setuid(uid)
       seteuid(euid)
       setruid(ruid)
       uid_t uid, euid, ruid;

       setgid(gid)
       setegid(egid)
       setrgid(rgid)
       gid_t gid, egid, rgid;

DESCRIPTION
       Setuid (setgid) sets both the real and effective user ID (group ID) of the current process to as specified.

       Seteuid (setegid) sets the effective user ID (group ID) of the current process.

       Setruid (setrgid) sets the real user ID (group ID) of the current process.

       These calls are only permitted to the super-user or if the argument is the real or effective ID.

SEE ALSO
       setreuid(2), setregid(2), getuid(2), getgid(2)

DIAGNOSTICS
       Zero is returned if the user (group) ID is set; -1 is returned otherwise.

4.2 Berkeley Distribution					   May 12, 1986 							 SETUID(3)