What is the difference between Ctrl-z and Ctrl-c in the terminal?

If we leave edge cases to one side, the difference is simple. Control+C aborts the application almost immediately while Control+Z shunts it into the background, suspended.

The shell send different signals to the underlying applications on these combinations:

• Control+C (control character intr) sends SIGINT which will interrupt the application. Usually causing it to abort, but this is up to the application to decide.

• Control+Z (control character susp) sends SIGTSTP to a foreground application, effectively putting it in the background, suspended. This is useful if you need to break out of something like an editor to go and grab some data you needed. You can go back into the application by running fg (or %x where x is the job number as shown in jobs).

  We can test this by running nano TEST, then pressing Control+Z and then running ps aux | grep TEST. This will show us the nano process is still running:

  oli     3278  0.0  0.0  14492  3160 pts/4    T    13:59   0:00 nano TEST
  

  Further, we can see (from that T, which is in the status column) that the process has been stopped. So it's still alive, but it's not running... It can be resumed.

  Some applications will crash if they have ongoing external processes (like a web request) that might timeout while they're asleep.

Ctrl+C is used to kill a process with signal SIGINT, in other words it is a polite kill .

Ctrl+Z is used to suspend a process by sending it the signal SIGTSTP, which is like a sleep signal, that can be undone and the process can be resumed again.

However when a process is suspended, we can resume it again by fg (resume in foreground) and bg (resume in background) , but I can't resume a killed process, that is a difference between using Ctrl+C & Ctrl+Z.

How can we view suspended processes?

The jobs command gives output like this:

[1]-  Stopped                 cat
[2]+  Stopped                 vi

How to kill a suspended process in background?

By using the kill command:

kill %n where n is the number displayed by the jobs command. So if I want to kill cat: kill %1.