#include "apue.h"static void	sig_usr(int);	/* one handler for both signals */intmain(void){	if (signal(SIGUSR1, sig_usr) == SIG_ERR)		err_sys("can't catch SIGUSR1");	if (signal(SIGUSR2, sig_usr) == SIG_ERR)		err_sys("can't catch SIGUSR2");	for ( ; ; )		pause();}static voidsig_usr(int signo)		/* argument is signal number */{	if (signo == SIGUSR1)		printf("received SIGUSR1\n");	else if (signo == SIGUSR2)		printf("received SIGUSR2\n");	else		err_dump("received signal %d\n", signo);}