#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sched.h>

int
main(int argc, char *argv[]) {
    int uid = getuid();
    int pid = atoi(argv[1]);
    int sched_fifo_min, sched_fifo_max;
    static struct sched_param sched_parms;

    if (!pid)
	pid = getpid();

    sched_fifo_min = sched_get_priority_min(SCHED_FIFO);
    sched_fifo_max = sched_get_priority_max(SCHED_FIFO);
    sched_parms.sched_priority = sched_fifo_min + 1;

    if (sched_setscheduler(pid, SCHED_FIFO, &sched_parms) == -1)
        perror("cannot set realtime scheduling policy");

    if (uid)
	setuid(uid);

    if (pid == getpid())
	execvp(argv[1],&argv[1]);
    return 0;
}