Terminal in full screen mode: how do I recover from "cat /dev/random"

Question

What are the ways I can regain control over my computer when I have terminal in full screen mode and type:

cat /dev/random

@DanielLawson - I'm learning OSX and experimenting. I hope to learn how to recover from a runaway process, which may happen in a developer environment (which I'm in) — makerofthings7, Sep 16, 2012 at 4:06
You can press the power button and hold it. The filesystem is journaled and you'll soon learn which programs don't save their files cleanly :-/ — bmike, Sep 16, 2012 at 18:55

nohillside · Accepted Answer · 2012-09-16 14:38:25Z

4

If you have Terminal.app open anyway (doesn't matter whether it's in fullscreen mode or not):

Cmd-T to create new tab/shell
ps aux | fgrep /dev/random to find the running cat (you can grep for cat as well but there might be more than one matching line)
kill <PID from above> (or kill -9 <PID>)

Just be patient, the system may be really slow (even on a multicore system as I've just found out).

answered Sep 16, 2012 at 14:33

nohillside♦

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Is "kill -9" a joke referring to 9 lives of a cat, or is it something else?
– makerofthings7
Sep 16, 2012 at 14:35
See man kill, -9 is the signal to send. By default, kill sends a "soft" termination (letting the application/command handle the termination itself). This may not work if the application is stuck in some loop and never gets to handle the signal. -9 terminates on OS level.
– nohillside ♦
Sep 16, 2012 at 14:37
Would killall cat not work?
– segiddins
Oct 3, 2012 at 14:41
1

There might be several cats running through the (process) jungle, no reason to commit felinicide...
– nohillside ♦
Oct 3, 2012 at 14:50
@makerofthings7 In general, you should at least try kill -TERM or kill -INT (which is the same as ^C) first; jumping straight to SIGKILL is often a bad idea.
– Blacklight Shining
Nov 22, 2012 at 1:11

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segiddins · Accepted Answer · 2012-09-16 04:00:33Z

1

Just tested this, type control-c in terminal, it should stop any running command.

answered Sep 16, 2012 at 4:00

segiddins

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Perhaps the keyboard buffer was still full for me... ctrl c had no effect
– makerofthings7
Sep 16, 2012 at 4:05
Really! I tried several times, and each time I was able to get out of 'cat' no problem.
– segiddins
Sep 16, 2012 at 4:06
I ended up going into activity monitor and killing the cat. Fortunately I only had to do it once
– makerofthings7
Sep 16, 2012 at 4:08
Fair enough. Seems like a strange thing to do, but I've seen (much) worse before.
– segiddins
Sep 16, 2012 at 4:10
You might need to reset the terminal with command-R.
– lhf
Sep 16, 2012 at 14:43

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2 Answers 2