From: anselm <anselm@...>
Date: 2007-04-16T19:20:07+09:00
Subject: Re: executing a system command and stopping it after a specified duration?

On Apr 15, 5:57 am, Robert La Ferla <robertlafe...@comcast.net> wrote:
> I'd like to run a system command and then stop it after specified
> amount of time (in seconds or milliseconds.)  What's the best way to
> do it?

I have this handy function ; it raises an exception on timeout/non
zero exit status, returns the result of the call
otherwise (ie. what the process output on $stdout). In case of timeout
it also attemts to kill the process (runs on Unix - no clue about
other platforms!) :

#
# Usage example :
#

files = run('find -mtime -7')

#
# Function :
#
def run(s, maxt = 10*60)
  begin
    pipe = IO.popen(s, 'r')
  rescue Exception => e
    $stderr << 'Execution of '+s+' has failed :' + e.to_s
    raise "run failed"
  end

  begin
    Timeout::timeout(maxt) do |t|
      a = Process.waitpid2(pipe.pid)
      if a[1].exitstatus != 0
        $stderr << 'Error while executing ' + s
        raise "run failed"
      end
    end
  rescue Timeout::Error => e
    $stderr << 'Execution of '+s+' has timed out. Killing subprocess'
    begin
      Process.kill('KILL', pipe.pid)
      pipe.close
    rescue Object => e
      $stderr << 'Failed killing process : ' + e.to_s
    end
    raise "run failed"
  end

  out = pipe.gets(nil)
  pipe.close
  out
end

I've edited it a bit to remove some of my specific dependencies - so
there might be typos here :)
It could be improved to also return the content of $stderr in case of
non-zero exit status.

Anselm