720 Chapter 34
q if (getpid() == getpgrp()) /* If process group leader */
fprintf(stderr, "Terminal FG process group: %ld\n",
(long) tcgetpgrp(STDERR_FILENO));
w fprintf(stderr, "Process %ld (%d) received signal %d (%s)\n",
(long) getpid(), cmdNum, sig, strsignal(sig));/* If we catch SIGTSTP, it won't actually stop us. Therefore we
raise SIGSTOP so we actually get stopped. */e if (sig == SIGTSTP)
raise(SIGSTOP);
}int
main(int argc, char *argv[])
{
struct sigaction sa;sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = handler;
r if (sigaction(SIGINT, &sa, NULL) == -1)
errExit("sigaction");
if (sigaction(SIGTSTP, &sa, NULL) == -1)
errExit("sigaction");
if (sigaction(SIGCONT, &sa, NULL) == -1)
errExit("sigaction");/* If stdin is a terminal, this is the first process in pipeline:
print a heading and initialize message to be sent down pipe */t if (isatty(STDIN_FILENO)) {
fprintf(stderr, "Terminal FG process group: %ld\n",
(long) tcgetpgrp(STDIN_FILENO));
y fprintf(stderr, "Command PID PPID PGRP SID\n");
cmdNum = 0;} else { /* Not first in pipeline, so read message from pipe */
u if (read(STDIN_FILENO, &cmdNum, sizeof(cmdNum)) <= 0)
fatal("read got EOF or error");
}i cmdNum++;
o fprintf(stderr, "%4d %5ld %5ld %5ld %5ld\n", cmdNum,
(long) getpid(), (long) getppid(),
(long) getpgrp(), (long) getsid(0));/* If not the last process, pass a message to the next process */if (!isatty(STDOUT_FILENO)) /* If not tty, then should be pipe */
a if (write(STDOUT_FILENO, &cmdNum, sizeof(cmdNum)) == -1)
errMsg("write");s for(;;) /* Wait for signals */
pause();
}
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––– pgsjc/job_mon.c