Why do we have to use all this shortcut to quit the programs in terminal ?
For example :
- ctrl+c in order to quit
top - ctrl+z in order to quit
man - ctrl+x in order to quit
nano
ctrl+c isn't suppose to kill the program ?
Add a comment
|
2 Answers
Because it's specified in POSIX, the IEEE norm for Unix-like computer systems.
Check Section 10.2 - Output Devices and Terminal Types of the POSIX.1 2008 (the latest) specification for all the shortcuts available.
To add up to your question, this is a brief explanation of what those shortcuts actually do.
When you press Ctrl-[letter], you are actually sending a signal to the process. A signal is a "flag" you provide to the process that gets interpretated and associated with an action.
Ctrl-C sends SIGINT, a signal that causes the process to terminate.
Ctrl-Z sends SIGTSTP, a signal this causes the process to suspend execution. In this case, it is resumable - try executing a command that will take a while and press Ctrl-Z; you'll see something in the lines of
[1]+ Stopped [your command].Type
fgin your Terminal and you'll see the process resuming, if it didn't end before resuming it.Ctrl-X, in this case, is the shortcut nano uses to exit the process. Incidentally, there is a signal associated to Ctrl-x, but it's not related to nano.
TL;DR It's specified in POSIX.
-
-
Would be very usefull to also add "bg" (background) for resuming a process in the background, i.e., keeping the terminal available for other commands– vanadiumJan 4, 2019 at 7:39
-
+z and +c are shell signals.
ctrl+z is not killing the program, it is sending it a signal (SIGTSTP) to suspend. Type fg to resume it. ctrl+c is another signal, this time the SIGINT to terminate. kbd+x is just a nano key binding.
