text: #include "apue.h"
  
  #define	BUFFSIZE	1024
  
  static void
  sig_tstp(int signo)	/* signal handler for SIGTSTP */
  {
  	sigset_t	mask;
  
  	/* ... move cursor to lower left corner, reset tty mode ... */
  
  	/*
  	 * Unblock SIGTSTP, since it's blocked while we're handling it.
  	 */
  	sigemptyset(&mask);
  	sigaddset(&mask, SIGTSTP);
  	sigprocmask(SIG_UNBLOCK, &mask, NULL);
  
  	signal(SIGTSTP, SIG_DFL);	/* reset disposition to default */
  
  	kill(getpid(), SIGTSTP);	/* and send the signal to ourself */
  
  	/* we won't return from the kill until we're continued */
  
  	signal(SIGTSTP, sig_tstp);	/* reestablish signal handler */
  
  	/* ... reset tty mode, redraw screen ... */
  }
  
  int
  main(void)
  {
  	int		n;
  	char	buf[BUFFSIZE];
  
  	/*
  	 * Only catch SIGTSTP if we're running with a job-control shell.
  	 */
  	if (signal(SIGTSTP, SIG_IGN) == SIG_DFL)
  		signal(SIGTSTP, sig_tstp);
  
  	while ((n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0)
  		if (write(STDOUT_FILENO, buf, n) != n)
  			err_sys("write error");
  
  	if (n < 0)
  		err_sys("read error");
  
  	exit(0);
  }
  