ast_comparator/test/student_data/handout/shlab-handout/cases/prev_2_tsh.c
/*
 * sigtstp_handler - The kernel sends a SIGTSTP to the shell whenever
 *     the user types ctrl-z at the keyboard. Catch it and suspend the
 *     foreground job by sending it a SIGTSTP.
 */
The kernel sends a SIGTSTP to the shell whenever
the user types ctrl-z at the keyboard. Catch it and suspend the
foreground job by sending it a SIGTSTP.
The kernel sends a SIGTSTP to the shell whenever the user types ctrl - z at the keyboard . Catch it and suspend the foreground job by sending it a SIGTSTP .
void sigtstp_handler(int sig)
{
   pid_t pid = fgpid(jobs);
   if(pid<=0)
      return;
   if(kill(-pid,SIGTSTP)<0)
   {
      unix_error("sigstp_handler error");
      return;
   }
   return;
}
void sigtstp_handler ( int sig ) { pid_t pid = fgpid ( jobs ) ; if ( pid <= 0 ) return ; if ( kill ( - pid , SIGTSTP ) < 0 ) { unix_error ( " " ) ; return ; } return ; }
sigtstp_handler - The kernel sends a SIGTSTP to the shell whenever
     the user types ctrl-z at the keyboard.
sigtstp_handler - The kernel sends a SIGTSTP to the shell whenever the user types ctrl - z at the keyboard .
//sending SIGTSTP signal to the foreground process //sending SIGINT signal to the foreground process