From: Nate Murray <jashmenn@...>
Date: 2006-11-21T05:35:07+09:00
Subject: Re: fork, trap and exec. Pickaxe typo?

Yeah, but how do I wait for an unknown amount of time? It would seem
that this would do it:

trap("CLD") {
  pid = Process.wait
  puts "Child pid #{pid}: terminated"
}

1.upto(4) do
  fork do
    exec("sleep 3 && echo \"hello $HOSTNAME #{Process.pid}\n\"")
  end
end

Process.waitall

But trap isnt always called on all the children.

Example output:

hello nate.cpo 4136

Child pid 4136: terminated
hello nate.cpo 4139

Child pid 4139: terminated
hello nate.cpo 4137

hello nate.cpo 4138

Child pid 4138: terminated

Notice that 4137 never called the trap callback even though
Process.waitall was called.

Hugh Sasse wrote:
> On Tue, 21 Nov 2006, Nate Murray wrote:
>
> > Hey All, I got this code straight from the PickAxe:
> >
> > But it doesnt word!
> > The CLD trap'ped call never executes.
> >
> >
> > Another question... If I perform the exec 4 times the trap call back
> > should be called four times, right?
> >
> > So this code:
> >
> > trap("CLD") {
> >   pid = Process.wait
> >   puts "Child pid #{pid}: terminated"
>     # exit
> > }
> >
> > 1.upto(4) do
> >   exec("echo \"hello $HOSTNAME #{Process.pid}\n\" ; sleep 5") if
> > fork.nil?
> > end
>
>   sleep 25
> >
> > Should call trap("CLD") four times, right?
> >
> > Thanks for your help in advance.
>
> that should do the job.  You didn't wait around for things to happen.
>         Hugh
> > 
> > 
> >