Why does this not kill remote process?

Question

The follow command works in a local terminal:

ps aux | grep "script.py" | awk {'print $2'} | xargs kill -2

But this command doesn't work remotely:

ssh -o ConnectTimeout=6 john@remote-pc ps aux | grep "script.py" | awk {'print $2'} | xargs kill -2

...even though script.py on remote belongs to john, the user we are ssh as. I can ping successfully and other commands are successful.

Only `ps aux` is running on the remote machine the rest is running on the local machine — Alan Birtles, Aug 03 '18 at 07:34
If I delete the final `xargs kill -2` then I still receive the print of the remote pid so I'm not sure you're correct. — JSStuball, Aug 03 '18 at 07:35
Why? If ps returns the correct string from the remote machine running grep and awk on the local machine will work correctly — Alan Birtles, Aug 03 '18 at 07:37

Alan Birtles · Accepted Answer · 2018-08-03T09:09:06.133

1

You need to escape the pipes to cause them to be passed to the ssh command rather than being executed by your local shell otherwise everything after ps aux is executed on your local machine.

ssh -o ConnectTimeout=6 john@remote-pc ps aux \| grep "script.py" \| awk {\'print $2\'} \| xargs kill -2

edited Aug 03 '18 at 09:09

answered Aug 03 '18 at 08:20

Alan Birtles

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Thanks that's great to know. In fact I discovered it was also necessary to escape the single quotes in the `awk` command when executed remotely. – JSStuball Aug 03 '18 at 09:01
@JSStuball yep, getting this right is tricky, for anything other than simple commands I tend to write a shell script instead: https://stackoverflow.com/questions/4412238/what-is-the-cleanest-way-to-ssh-and-run-multiple-commands-in-bash – Alan Birtles Aug 03 '18 at 09:10

Why does this not kill remote process?

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