[SOLVED] Cleaning up this kill command

laredotornado · 07-19-2011, 02:58 PM

Hi,

Using Ubuntu 11.04. I use this command to kill frozen Flash processes ...

Code:

pgrep -P1 -f 'npviewer\.bin' | xargs kill -9

IF there are no hung processes, I get the error ...

Code:

Usage:
  kill pid ...              Send SIGTERM to every process listed.
  kill signal pid ...       Send a signal to every process listed.
  kill -s signal pid ...    Send a signal to every process listed.
  kill -l                   List all signal names.
  kill -L                   List all signal names in a nice table.
  kill -l signal            Convert between signal numbers and names.

Anyway I can prevent these errors from printing out if there are no matching processes? Thanks, - Dave

modonnell · 07-19-2011, 06:04 PM

I have no problem with this so let's check a few things. For starters, find out what's actually being executed when you issue the "pgrep" command to the shell. Assuming you're using bash you could say:

type pgrep

...and on my machine it reports that when I say "pgrep" it would load /usr/bin/pgrep. If it instead reported some alias or shell script in some unexpected location we'd first want to take care of that. Sometimes your $PATH can be misconfigured such that some unexpected script or binary is being found and executed instead of the one you want.

Then find out what version you're running. On my system I can say this:

pgrep -V

...and it reports:

pgrep (procps version 3.2.8)

...which may or may not be similar to what you're running. If your version is dramatically older then you might want to try using your package manager to pull a newer version on board before spending too much time analyzing a pgrep bug that may already be fixed.

laredotornado · 07-20-2011, 08:20 AM

I just edited my post. I incorrectly listed the command that was giving that error. It is corrected now, but to repeat, it is

Code:

pgrep -P1 -f 'npviewer\.bin' | xargs kill -9

So the question is, if there is nothing piped into the "kill" command, can I get it to stop complaining? - Dave

David the H. · 07-20-2011, 09:03 AM

You are aware that pgrep comes with a sister command, "pkill", right? No need to bother with xargs.

modonnell · 07-21-2011, 05:53 AM

David the H. wrote:

Quote:

You are aware that pgrep comes with a sister command, "pkill", right? No need to bother with xargs.

...and that's likely the answer you want, of course. (I was getting to that! :-) But in keeping with your previous approach, this less elegant command would also work:

for pid in $(pgrep -P1 -f 'npviewer\.bin'); do kill -9 $pid; done

...which would do nothing when no matches are reported.