#include	"apue.h"#include	<sys/wait.h>static void	sig_cld(int);intmain(){	pid_t	pid;	if (signal(SIGCLD, sig_cld) == SIG_ERR)		perror("signal error");	if ((pid = fork()) < 0) {		perror("fork error");	} else if (pid == 0) {		/* child */		sleep(2);		_exit(0);	}	pause();	/* parent */	exit(0);}static voidsig_cld(int signo)	/* interrupts pause() */{	pid_t	pid;	int		status;	printf("SIGCLD received\n");	if (signal(SIGCLD, sig_cld) == SIG_ERR)	/* reestablish handler */		perror("signal error");	if ((pid = wait(&status)) < 0)		/* fetch child status */		perror("wait error");	printf("pid = %d\n", pid);}