How to transform multiple line into one line in bash stdout?

Question

I sometimes do this in my shell :

sam@sam-laptop:~/shell$ ps aux | grep firefox | awk '{print $2}'
2681
2685
2689
4645

$ kill -9 2681 2685 2689 4645

Is there a way I can transform the multiple lines containing the PIDs into one line separated by spaces ? (It's a little bit annoying to type the PIDs every time and I really would like to learn :) )

Thanks a lot.

Answer 1

The easy way for this is using xargs

ps aux | grep firefox | awk '{print $2}' | xargs kill -9

This will invoke the kill command with all pids at the same time. (Exactly what you want)