Can someone tell me why this shell script isn't working the way I want it to

Question

ssh hostname ps aux| egrep '.*python' | grep -v 'grep'| awk '{print $2}'| xargs kill -KILL

When I run this I get the error message "kill: No such process"

But when I run this:

ssh hostname ps aux| egrep '.*python' | grep -v 'grep' |awk '{print $2}'| xargs echo

It correctly prints the pid. And also

ps aux| egrep '.*python' | grep -v 'grep'| awk '{print $2}' | xargs kill -KILL

works correctly on the localhost.

Answer 1

As the others have pointed out, you can't just run a piped command through ssh without putting the command sequence in quotation marks.

But there's an even easier way to do what you want:

ssh hostname pkill python

The pkill command will handle all of the process grepping for you.

Answer 2

Your command is only running ps aux on the remote host, everything else gets executed locally.

change it to

ssh hostname "ps aux| egrep '.*python' | grep -v 'grep'| awk '{print \$2}'| xargs kill -KILL"

The usage of the quotes sends the entire command over to the remote host. And then you have to add the \ in front of the $2 because youre inside double quotes, and those single quotes are just characters at that point

Answer 3

It's because only first command (ps aux) is being provided to ssh as args. Try to use quotes: ssh hostname "ps aux| egrep '.*python' | grep -v 'grep'| awk '{print $2}'| xargs kill -KILL"

In this case "ps aux| egrep '.*python' | grep -v 'grep'| awk '{print $2}'| xargs kill -KILL" would be passed to ssh command as 2nd argument

Answer 4

It can't work that way, the output from ssh is processed on your local machine. So the call to kill will try to terminate a process on your machine, not on the remote machine.

You can try to use the expect tool to solve the problem.