Seperating lines in a shell script

slackwarefan · 10-16-2009, 03:48 AM

Greetings all,
Due to another issue that I'm having with firefox, specifically the flash plugin which keeps causing it to freeze, I'm forced rather frequently to stop firefox with "kill -9" and restart it. I decided to try to write a shell script to automate this.

At this point, I have this

Code:

ps -A | grep firefox-bin | cut -c -6

Which lists all running processes, selects only the lines for firefox, then cuts off everything except for the process numbers. The only problem that I'm having is that most of the time there are two firefox-bin processes, and I get two different numbers on two different lines. How can I run kill -9 on one of these at a time?

I'd like to be able to automate it such that I run just one command and it kills firefox, then restarts it for me.

Thanks in advance,
-Primux

rizhun · 10-16-2009, 03:54 AM

You were nearly there...

Try this:

Code:

$ ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {}

To get it to start FireFox after killing it, add the following:

Code:

$ ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {} && /path/to/firefox/executable

See the man page for xargs for info:

Code:

$ man xargs

Happy hacking

vonbiber · 10-16-2009, 03:59 AM

Quote:

Originally Posted by slackwarefan

Code:

ps -A | grep firefox-bin | cut -c -6

Which lists all running processes, selects only the lines for firefox, then cuts off everything except for the process numbers. The only problem that I'm having is that most of the time there are two firefox-bin processes, and I get two different numbers on two different lines. How can I run kill -9 on one of these at a time?

to kill the first process insert

Code:

| head -n1

after your grep so that you have

Code:

ps -A | grep ...| head -n1 | cut ...

i92guboj · 10-16-2009, 04:02 AM

You probably want to look into pidof.

Code:

pidof <whatever> | xargs kill -9 && <whatever else>

ArfaSmif · 10-16-2009, 06:24 PM

Does Slackware have the "killall" command? If so this might be another way to do it.

slackwarefan · 10-16-2009, 07:38 PM

Yes, slackware does have the killall command; however when firefox hangs/freezes as it does due to the flash plugin, I need to use

Code:

kill -9

in order to kill it, kill or killall alone cannot do it, I need "-9" or the force parameter to successfully do it.

I think based upon what the others have posted though, that I should be able to pull it off. I'm not at my computer now, but I'm going to look into the xargs command, and and see what I can do with that.

Also, I can't believe that I forgot about the "head" command, silly me. :-p

Thanks everybody,
-Primux

Elv13 · 10-17-2009, 12:02 AM

killall -9 will work

but the right way or doing a line per line script is:

Code:

#/bin/bash
#^^It is important, this time to add this line or it may not work
IFS=`echo -en "\n\b"`
for LINE in `ps`; do
   echo My line is $LINE
done

jlinkels · 10-17-2009, 07:41 AM

How complicated!

Code:

pkill -9 firefox-bin

pkill greps for the processes containing this name and kills them.

jlinkels

slackwarefan · 10-17-2009, 10:35 PM

Quote:

Originally Posted by rizhun

You were nearly there...

Try this:

Code:

$ ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {}

To get it to start FireFox after killing it, add the following:

Code:

$ ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {} && /path/to/firefox/executable

See the man page for xargs for info:

Code:

$ man xargs

Happy hacking

Thank you very much for the idea. The only problem with this, which comes not from your contribution, but from my original code, is that if I use cut with the -6 option, and the process is only 5 digits long, I get

Code:

primux@slaxor:~$ ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {}
kill: can't find process "13043 "

Now if I change the code to "cut -c -5", it works fine. I would just change the code, but sometimes the process numbers do get up to six digits.

Should I set it up to try it with 6 first, then run the same string of commands again with -5? Or should I try to figure out how to make the script figure out how many digits the process number is, and then make the 5 or 6 arguments for cut be variables? Would this be possible? *head scratch*

I'm pretty sure it'd work if I just wrote it like this

Code:

ps -A | grep firefox-bin | cut -c -5 | xargs -i kill -9 {}
ps -A | grep firefox-bin | cut -c -6 | xargs -i kill -9 {}

But it's kind of brutish, and I really don't like to program in that style. I'd like to make something elegant that just works perfectly, but I'm not quite sure if it's possible.

It is kind of aggravating that when you run kill through xargs, that it recognizes the space as part of the process number. Oh! (I just got an idea while typing), is it possible to make xargs ignore that space? Or rather to ignore that space without affecting the way it reads the input from STDIN? I read the man page, and I know that you can change the way that it decides what counts as a separator, but I don't know if it would change the way it takes the input or executes kill.

/me starts reading more about bash scripting
Thanks everybody!
-Primux

slackwarefan · 10-18-2009, 01:21 AM

Ok, I got it to work. If anyone else has this problem, here's the code I used . . .

Code:

#! /bin/bash

var=`ps -A | grep firefox-bin | cut -c -6`
var+=1
letter_seperator=" "
if $var | grep "$letter_seperator"
then
cutnum=5
else
cutnum=6
fi

ps -A | grep firefox-bin | cut -c -"$cutnum" | xargs -i kill -9 {}

/path/to/firefox &

exit 0

For some reason, killall does not work when firefox freezes because of the flash plugin.

I'm not sure about pkill, I wish I'd heard of/remembered that before I thought up all of this.

Anyways, thanks to everybody that gave me ideas. I hope this can help someone else. I mean, am I the only one to whom this happens? *shrug*

Thanks again everybody,
-Primux

rizhun · 10-18-2009, 07:08 AM

You could also use 'awk' to get the first "field", then it doesn't matter how many digits are in the PID:

Code:

$ ps -ef | grep firefox-bin | awk '{printt $1}' | xargs -i kill -9 {}

Glad I could help.

jlinkels · 10-18-2009, 07:50 AM

Heloooo... did any read this? Or trying to do it difficult even if it can be done the easy way? Or is pkill a Debian speciality?

Quote:

Originally Posted by jlinkels

How complicated!

Code:

pkill -9 firefox-bin

pkill greps for the processes containing this name and kills them.

jlinkels

heiko · 10-18-2009, 03:10 PM

No, on my Slackware 13 there is pgrep as well as pkill. I think one could do the task with these commands conveniently.

Quote:

Originally Posted by jlinkels

Heloooo... did any read this? Or trying to do it difficult even if it can be done the easy way? Or is pkill a Debian speciality?