From: Brian Candler <B.Candler@...>
Date: 2005-07-06T18:27:25+09:00
Subject: Re: Exececuting another application from within ruby

On Tue, Jul 05, 2005 at 06:20:38PM +0900, nobuyoshi nakada wrote:
> > 'atexit' script you've previously defined will run in both parent and child.
> 
> No, system nor exec don't invoke at_exit handlers.
> 
>   $ ruby -e 'at_exit{puts "#$$ exiting"}; system("echo foo")'
>   foo
>   1020 exiting

It's clear that if the exec succeeds then no at_exit handler can possibly be
called; more interesting is the case if it fails. It looks like the at_exit
handler is not called there - I hadn't tested it before.

$ ruby -e 'at_exit{puts "#$$ exiting"}; system("zxcvzxcv"); p $?'
#<Process::Status: pid=31775,exited(127)>
31774 exiting
$ 

However:

$ ruby -e 'at_exit{puts "#$$ exiting"}; Process.waitpid(fork {exec("zxcvzxcv")}); p $?'
44096 exiting
-e:1:in `exec': No such file or directory - zxcvzxcv (Errno::ENOENT)
        from -e:1
        from -e:1:in `fork'
        from -e:1
#<Process::Status: pid=44096,exited(1)>
44095 exiting

which is what I was expecting. Anyway, it's a useful mental note to keep :-)

Cheers,

Brian.