SETUID(2) BSD Programmer's Manual SETUID(2) setuid, seteuid,
setgid, setegid - set user and group ID #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); 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, set- gid() will