Shell script to kill a process

Question

I need to implement a shell script that kills a process. The problem is that I need to do a conditional to be able to see if the process is running or not.

This is my code, but it is not working:

#!/bin/sh

if [ -x  "MY_PROCCESS_NAME"]; then
    killall MY_PROCCESS_NAME
else
    echo "Doesn't exist"
fi

This is the error:

line 3: [: missing `]'

Solution

to check if a process is running on mac os x you can use:

pid=$(ps -fe | grep 'process name' | grep -v grep | awk '{print $2}')

if you want to reduce the number of shell scripts you can enclose one of the characters of the name of the process in square brackets:

pid=$(ps -fe | grep '[p]rocess name' | awk '{print $2}')

combined in your test this would look like:

pid=$(ps -fe | grep '[p]rocess name' | awk '{print $2}')
if [[ -n $pid ]]; then
    kill $pid
else
    echo "Does not exist"
fi

it's a little more complicated than you would need to do under linux as you generally have the 'pgrep' command, which is the rough equivalent of the 'ps -fe | grep ... | grep -v grep'

Comments

[Shawn Chin]

If you're going to use awk anyway, skip the grep -- awk '/[p]rocess_name/{print $1}'

[Ana]

Thanks for the answer!. When I run your code, I am always obtaining the "Does not exist" message, even if the process is running.

[Anya Shenanigans]

Sounds like the pattern match is not finding your process. Make sure that "ps -fe | grep '[p]rocess name'" gives you a line matching the process, so for example if you were looking for WindowServer then the line would read "ps -fe | grep '[W]indowServer'"

[Ana]

I had an issue with the script, now is fine, but when I run the script, it kills all my machine :S, I only see the desktop image, the other programs and process disapear.

[Anya Shenanigans]

It's the usual problem of making sure that you only match your process, and not anything else - e.g. If your program is called 'inder' then the Greg of the process will also pick up on 'Finder', which would kill your desktop!

[Ana]

I changed the first line for this an it worked!pid=$(ps -ef | awk '/[p]rocess name/{print $2}')

[Matt Wielbut]

This doesn't work - the first column running ps -fe is the UID, not the PID (the second column). You should end the command with awk '{print $2}' - note the 2