Bash Shell Awesomeness - Mass Killing Processes (On Ubuntu) | Hacker News Reader

Bash Shell Awesomeness - Mass Killing Processes (On Ubuntu)

skorks.com

9 pointsaskorkin15 comments

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You could just use killall.

http://linux.die.net/man/1/killall

Hey, You're right! Never noticed that -u option.

I must use killall 100 times a day :)

Or you could ask ps to do most of the work for you:

  ps -u www-data -o pid --no-headers

That gives me just the PIDs of the processes run by www-data.

Makes you wonder how much shell script code is written every year by people that have not yet cracked the manual on section '1'.

So much good stuff in there.

Good reminder to do a periodic review of that stuff, not all the options are easy to remember if you don't use them frequently enough.

Actually, I can never remember any of the options. I find myself doing man FOO all the time and usually work under the assumption that there's probably already an option to do the thing I'm trying to do.

Kudos to the original poster. That sort of combining of small tools is what the NIX command-line is all about.

Thats a great one as well, didn't even realise ps could do that

... or use pkill:

  pkill -9 -U lusername

Unlike in Linux, in most unices killall(1) terminates all the processes

God, that brings back memories of administrating Solaris boxes in high school. Once you reboot a primary web server twice, you never do it again.

> Unlike in Linux, in most unices killall(1) terminates all the processes

Hehe... That reminds me of the day I learned that you shouldn't put . in your path, especially in the front.

It turns out that (old?) Red Hat machines had a script 'killall' in their /etc/init.d ...

su to that user and "kill 0" or safer "kill -1".

He should really use awk instead of cut. or killall and for awesomeness, he should use zsh. bash is what you use for mediocrity.

Why awk instead of cut?

awk treats input as lines and columns, therefore it would be more accurate than cut that treats input as lines and characters.

You don't want charaters this to that, what you do want is column 2.

cut -d ' ' -f 2

Who modded that down? He really should be using awk instead of cut. It has better readability: "{print $2}" to print the second field vs. a set of magic numbers denoting a character field. It's vastly easier to write (again, the "second field" is intuitive). It's also more generally useful, meaning that it's a better tool to know; cut is very primitive.

That said, there are better ways still to solve this problem. Some of them were detailed above. One that wasn't was the fact that GNU ps has lots of filtering options itself, in this case:

  ps -eo pid -U 1002

Does the work of the grep and cut from the original for you.

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