#include <unistd.h>#include <time.h>#include <sys/select.h>unsignedsleep(unsigned nsec){	int n;	unsigned slept;	time_t start, end;	struct timeval tv;	tv.tv_sec = nsec;	tv.tv_usec = 0;	time(&start);	n = select(0, NULL, NULL, NULL, &tv);	if (n == 0)		return(0);	time(&end);	slept = end - start;	if (slept >= nsec)		return(0);	return(nsec - slept);}