What to do when Ctrl-C won't kill running job?

Question

Sometimes, processes ignore the SIGINT signal sent by Ctrl-C in Bash. For instance, man and vi. Assuming you don't want to google or read the manual on how to exit the running process, is there any key sequence that will always work (without leaving the terminal)?

score 202 · Accepted Answer · edited Jun 18 '18 at 21:07

202

Send the SIGQUIT signal with Ctrl+\.

.. $ sleep 10
^\Quit

→ This is equivalent to kill -3 pid. Programs run in user-space don't ignore sigquit.

There is also a set of Magic SysRq keyboard shortcuts. One of the more interesting ones is this: Alt+SysRq+k. It kills every process on the current virtual console. If one of your ttys is completely and utterly broken, this can be used to go back. On the tty running X.org, it can be used to kill X without mercy.

The SysRq key is, on most keyboards, the same as the Print Key. On my notebook, it can be invoked using the Fn key; I.e. Alt→Fn→Print→k in that order.

Here are some of the basic process management shortcuts:

Ctrl+Z: pause a process (plus bg to resume in the background, fg to raise to foreground)
Ctrl+C: politely ask the process to shut down now
Ctrl+\: mercilessly kill the process that is currently in the foreground
Alt+SysRq+s: Write data to disk (always do this before killing anything important)
Alt+SysRq+s, k: mercilessly kill all current processes on a given virtual console
Alt+SysRq+s, b: mercilessly reboot without unmounting,
Alt+SysRq+r, e, i, s, u, b: Safely reboot even if the system is utterly broken,

Note: Ctrl+Z, in contrast to Ctrl+C and Ctrl+\, also works for man, vi, less, and the like.

When in doubt, the follwing procedure will almost always work:

~$ sleep 10
^Z
[5]+  Stopped              sleep 10
~$ ps
  PID TTY          TIME CMD
 4804 pts/0    00:00:00 bash
 6207 pts/0    00:00:00 sleep
 6208 pts/0    00:00:00 ps
~$ kill -9 6207
[5]+  Killed                  sleep 10
~$

^Z of course indicates that Ctrl+Z has been pressed.

For a more in-depth look at Shells and Terminals, also see my answers on:

edited Jun 18 '18 at 21:07

answered Nov 20 '10 at 12:07

Stefano Palazzo

86,783

3

Works for "sleep 10" but still doesn't work for "man" or "vi". Obviously "kill -9 pid" does work at killing both processes. Am I missing something? – Olivier Lalonde Nov 20 '10 at 12:14
3

Ctrl+Z works with things like less, man, vi and so on. You can then kill them by doing a ps to see their process id and kill them using kill pid or, if you don't care about other instances of the program, killall vi. In any case, Ctrl-Z always seems to work. – Stefano Palazzo Nov 20 '10 at 12:33
5

You can also do kill %% to kill the last job and kill %5 where 5 is the job number shown in jobs. – Olivier Lalonde Nov 20 '10 at 13:43
4

Ctrl-\ sends a SIGQUIT, not a SIGKILL. There are some important differences between SIGQUIT and SIGKILL. http://en.wikipedia.org/wiki/SIGQUIT – Juliano Nov 20 '10 at 16:44
Juliano, I feel a bit silly now.. But i've edited the answer. Thank you! – Stefano Palazzo Nov 20 '10 at 17:49
Never ever do Alt+SysRq+b. Instead do Alt+SysRq+reisub to prevent damage to your system. – Anonymous Nov 01 '11 at 23:50
1

There is no limitation that programs run in userspace have to honour SIGQUIT. C-\ does not "mercilessly kill the process that is currently in the foreground" any more than C-c does, both are trappable. – Chris Down Mar 06 '13 at 08:11
On laptops without a print key, how do we get Sysrq? For Surface pro keyboards could it be Fn + Space? – CMCDragonkai Nov 30 '15 at 07:44
Does Alt+SysRq+r, e, i, s, u, b mean pressing r,e,i,s,u,b in sequence? And not holding it down. – CMCDragonkai Nov 30 '15 at 08:09
@CMCDragonkai Yes, it means holding down Alt and SysRq and then pressing r, e, i, s, u and b in sequence. The SysRq key could be anywhere on your keyboard, I'm not sure how you'd find out which one it is. – Stefano Palazzo Nov 30 '15 at 08:12
@StefanoPalazzo Could you correct the broken images? – kenorb Dec 23 '16 at 17:02
4

How do I press Ctrl+\ when there is no \ key in my keyboard layout? – Forivin Jan 19 '17 at 09:49
can we catch CTRL+Z on node js using process.on('eventName')? – Alok Deshwal Jan 30 '21 at 23:36
How am I just learning about this?? +1+1 – Matt Alexander Jan 28 '22 at 14:34
None of these keys are working for me. – Vin Raghav Mar 03 '22 at 09:14

score 18 · Answer 2 · edited Nov 01 '11 at 20:47

18

You can try Ctrl+\

edited Nov 01 '11 at 20:47

Kris Harper

13,477

answered Nov 20 '10 at 12:06

Benjamin

259

2

Doesn't work with either man or vi. – Hippo Nov 20 '10 at 18:41
1

worked ubuntu 16.04 – kRazzy R Feb 13 '18 at 22:24
I had to hit Ctrl+\ twice before it did anything. However, it core dumped. – joatd Oct 28 '22 at 11:48

score 11 · Answer 3 · answered Nov 20 '10 at 20:18

Sometimes the CTRL+C is getting sent to the wrong program or input channel. This is especially common with editors such as vi, with commands with piped output, complex bash commands involving loops, etc.

A simple, quick solution is to suspend the job CTRL+Z and then kill it by job number: kill %1 or kill -9 %1, etc.

kenorb · Answer 4 · 2016-05-19T08:11:22.490

Try one of these:

Ctrl+4

Ctrl+\

Or:

Ctrl+Z and then run:

kill %1

Where %1 is the number of job which was returned when you pressed Control-Z. Add -9 to force the kill.

When you're in text console, you could also try: Ctrl-SysRq. The kernel should kill the process.

Or SysRq-k, kill all processes on the current virtual console (can kill X and svgalib programs as well).

Note: When magic SysRq keys are used to kill a frozen graphical program, the program has no chance to restore text mode. This can make everything unreadable.

See: Magic SysRq key and its command combinations.

score 4 · Answer 5 · edited Nov 20 '16 at 21:24

4

It's possible, that you changed the shortcut of copy from:

CTRL+SHIFT+C

To

CTRL+C

That way, when you try to kill a process, the CTRL+C doesn't work.

Try to replace the copy shortcut to CTRL+SHIFT+C.

edited Nov 20 '16 at 21:24

TheOdd

3,012

answered Nov 20 '16 at 19:36

Minter

51

2

Changing copy shortcut is irrelevant to force a process to be terminated! – SuB Nov 20 '16 at 20:13
Can you please expand on your answer a little? Step by step would be ideal, primarily so the OP can follow along with your suggestion. :) – AnotherKiwiGuy Nov 20 '16 at 21:17
1

This actually helped me. I'm used to CTRL+C on MacOS, and didn't realise the Ubuntu command was CTRL+SHIFT+C – dǝɥɔS ʇoıןןƎ Feb 14 '19 at 16:10
I never realized that is what I did! Thanks. CTRL+SHIFT+C works – TetraDev Jan 29 '21 at 02:49
This exactly what I did ><! Thank you! – Jet Blue May 20 '21 at 22:06

antivirtel · Answer 6 · 2010-12-30T20:36:08.140

3

To quit from man, use q To leave vi use :q

edited Dec 30 '10 at 20:36

answered Nov 20 '10 at 22:46

antivirtel

3,645

score 1 · Answer 7 · edited Jul 26 '20 at 09:34

1

Open Terminal → Preferences → Shortcuts and search if by mistake you have replaced any key with Ctrl+C.

edited Jul 26 '20 at 09:34

Kulfy

17,696

answered Jul 26 '20 at 03:22

Manas kumar

19

score -1 · Answer 8 · edited Jun 18 '18 at 14:30

-1

Try Ctrl+Alt+Backspace

If you are using ubuntu 10.04 you wanna enable this key to work.

To enable Control-Alt-Backspace

Goto System-->Preferences-->Keyboard

Select the Layouts tab and click on the Layout Options.

Select Key sequence to kill the X server and enable Control + Alt +Backspace.

Note:

Pressing Ctrl-Alt-Backspace will restart your X server.

edited Jun 18 '18 at 14:30

Eranda Peiris

751

answered Nov 20 '10 at 11:56

karthick87

81,947

Edited the question to make it clear I want to kill the process from within the terminal. – Olivier Lalonde Nov 20 '10 at 12:04

What to do when Ctrl-C won't kill running job?

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