From: Moritz Reiter <mreiter@...>
Date: 2006-11-24T19:41:15+09:00
Subject: Re: invoke system command from within a method

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Moritz Reiter wrote:
> Hi all,
> 
> I am new to Ruby and want to make a Ruby script for the network
> configuration of my notebook as an exercise. Now I encountered a problem
> which is pretty strange to me:
> 
> I want to invoke '/etc/init.d/networking restart' from within my Ruby
> program. If I create a file with the line
> 
> %x{ /etc/init.d/networking restart }
> 
> it works like I would expect. The networking init script gets invoked
> and correctly processed.
> 
> But if I do something like this:
> 
> -->8--
> class Netconf
> 	def restart
> 		puts %x{ /etc/init.d/networking restart }
> 	end
> end
> 
> netconf = Netconf.new
> netconf.restart
> --8<--
> 
> I get some output from the init script but it doesn't seem to actually
> do anything. It does not reconfigure my eth's in oppostion to the
> behaviour described above if don't make the system call from within a
> method.
> 
> I would be very glad if anyone could give me a hint or point me to some
> documentation to enlighten me.
> 
> Best Regards,
> 

Okay, now I know what went wrong. I should have told you the whole
story: In my script I rewrite /etc/network/interfaces and then invoke
the init script. My fault was, that I didn't close the File handler for
/etc/network/interfaces before starting the init script. So the init
script invoked ifdown and ifup but ruby did not write the new content of
/etc/network/interfaces to the harddisk yet, so ifup had no useful data
to do its job.

Damn, I learned my lesson: Always close your files as soon as you have
finisehd writing to them.

Sorry for bugging you all.

Regards,

- --
Moritz Reiter <mreiter@agrav.org>

GPG key fingerprint:
https://luna.agrav.org/~mo/gpg/

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