I'm using Mac OS X Terminal. And I use Ctrl+Z or Ctrl+C to stop some programs. But I realized that I don't know what they're exactly doing. What are they and what's the difference between them?
Control+Z is used for suspending a process by sending it the signal SIGSTOP, which cannot be intercepted by the program. While Control+C is used to kill a process with the signal SIGINT, and can be intercepted by a program so it can clean its self up before exiting, or not exit at all.
If you suspend a process, this will show up in the shell to tell you it has been suspended:
[1]+ Stopped yes
However, if you kill one, you won't see any confirmation other than being dropped back to a shell prompt. When you suspend a process, you can do fancy things with it, too. For instance, running this:
fg
With a program suspended will bring it back to the foreground.
And running the command
bg
With a program suspended will allow it to run in the background (the program's output will still go to the TTY, though).
If you want to kill a suspended program, you don't have to bring it back with fg first, you can simply do the command:
kill %1
If you have multiple suspended commands, running
jobs
will list them, like this:
[1]- Stopped pianobar [2]+ Stopped yes
Using %#, where # is the job number (the one in square brackets from the jobs output) with bg, fg, or kill, can be used to do the action on that job.
make a summary：
|
Ctrl + Z |
pause a job | 暂停任务 |
| Ctrl + C | terminates a job | 终止任务 |