From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2003-02-20T00:06:22+09:00
Subject: Re: I need to check if a process is running

On Wed, 19 Feb 2003, gp wrote:

> Hi,
>
> I need to check if a process is running.
> I have this code for this:
>
> ------------------------------------------
> pid="2212"
> cmd="ps -f p "+pid
> out=`#{cmd}`
> lines=out.split(/\n/)
> if (lines.length==1) then
>   print "Process with PID="+pid+" doesn't running.\n"
> end
> if (lines.length==2) then
>   print "Process with PID="+pid+" is running.\n"
> end
> ------------------------------------------
>
> Is there any other method for this?
> Is there any possibility to check this directly with ruby?

Process.kill(0, pid):

(kill with a signal of 0 sees if the process is still alive)

irb(main):001:0> Process.kill(0,$$)
1
irb(main):002:0> Process.kill(0,$$+1)
Errno::ESRCH: No such process
        from (irb):2:in `kill'
        from (irb):2
irb(main):003:0> exit

>
> Thanks,
> Gian Paolo
>
>
>
        Hugh