What is the difference between exiting a process via Ctrl+C vs issuing a kill -9 command?

Question

I know I can kill any process with kill -9 command . But sometimes i see that even if I have terminated a program with CTRL+C , the process doesn't get killed . So I want to know the difference between kill -9 vs CTRL+C

Solution

^C send the interrupt signal, which can be handled by a program (you can ignore it)

kill -9 send the sigkill signal which kills the program that you can't handle.

That's why you can't kill some programs with ^C

Comments

[Gilles 'SO- stop being evil']

See also What causes various signals to be sent?

[vonbrand]

One critical difference is that "well behaved" programs will catch ctrl-C and clean up after themselves (detach from any shared resources, destroy temporary files, reset the terminal to a sane state), SIGKILL doesn't give them that chance. BTW, it can happen that a program is stuck in an unkillable state inside the kernel.

[ams]

@l0b0: ^C sends SIGINT. kill (without -9) sends SIGTERM. Both those work the same, and can be handled by the program, but they're independent signals.

[ams]

If ^C doesn't work then you should try kill next, and then only kill -9 if you have to. The difference is that kill on it's own gives the program chance to clean up its files and whatnot. kill -9 just removes it without asking nicely.

[l0b0]

Aka. SIGINT (thanks @ams) and SIGKILL