I want to stop several processes using awk.My command is like this:sudo ps -ef|grep wget |grep -v grep|awk '{print $2;sudo kill -STOP $2}'I want to stop all processes which is running wget. $2 of awk means the pid of each process.But I find that it doesn't work.The state of process remains the same.They are still running.Instead , I modified this command:sudo ps -ef|grep wget |grep -v grep|awk '{print $2}'|xargs sudo kill -STOPit works! So , anyone can tell me the difference of them ? 
kill several processes using awk tools
awk;grep;kill