From: "ara.t.howard" <ara.t.howard@...>
Date: 2008-06-03T01:07:04+09:00
Subject: Re: Traping signals on child processes


On Jun 2, 2008, at 8:59 AM, Mário Lopes wrote:

> Hi,
>
> I currently have a Ruby process that spawns another process through a
> system() call in order to run an application from the command line.  
> The
> child process should not be aborted by INT signals and therefore the
> parent process shall wait for it to finish before exiting.
>
> In order to do so I tried trapping the INT signal but since system  
> runs
> in the foreground of the main process it seems that the application
> that's being called gets the INT signal nevertheless, despite being
> trapped in Ruby. The other approach I took was spawning a process in  
> the
> background and then waiting for it to finish but this approach adds a
> lot of complexity due to shared code that can't be run twice.
>
> What's the best approach to accomplish this? For the sake of  
> simplicity
> I'll leave a very simple example of what I want to do
>
> Start main process
>  Start system/child process
>    INT signals can't stop whatever the system call is doing
>  End system/child process
>  If INT signal detected, exit, otherwise, continue running
> End main process
>
> Any ideas or suggestions to accomplish such are most welcome.
>
> Thanks,
>
> Mário


trap( :INT ){ warn "can't do that" }

fork { exec command }
Process.wait

if the child installs it's own signal handler you are hosed.

a @ http://codeforpeople.com/
--
we can deny everything, except that we have the possibility of being  
better. simply reflect on that.
h.h. the 14th dalai lama