From: Craig Beck <craigbeck@...>
Date: 2006-06-22T12:13:11+09:00
Subject: Re: exec() not returning to ruby

Great!

system did the trick

between php, ruby, linux and mac osx at home, c# and windows at work  
I have a hard time switching modes and remembering which is which.

On Jun 19, 2006, at 10:26 PM, gwtmp01@mac.com wrote:

>
> On Jun 20, 2006, at 12:27 AM, Craig Beck wrote:
>
>> I've got some code like this:
>>
>> sources = File.new 'file_list.txt'
>> sources.each do |src|
>> 	exec "mkdir #{some_dest}" unless File.exists some_dest
>> 	exec "svn export #{src} #{some_dest}"
>> end
>> puts 'Done.'
>>
>> The problem is that ruby calls 'svn export' once for the first  
>> line of sources and exits without looping through subsequent  
>> sources or getttng to the line "puts 'Done.'"
>>
>> exec works just fine with the "mkdir" call.
>>
>> A couple of things:
>> 1. I'm on Windows Server 2003
>
> I'm not a windows guy so I don't know exactly how exec is  
> interpreted on Windows, but on the Unix side:
>
> exec causes the currently running program (i.e. Ruby) to be  
> replaced with the new command.
> Your "svn" command doesn't run because the first exec effectively  
> replaced the Ruby interpreter with
> "mkdir".  Sort of like invasion of the body-snatchers.  First the  
> process is running Ruby and then it
> is running "mkdir" and Ruby is gone.
>
> The Unix idiom to handle what you want to do is to call fork first  
> to create a child process and then
> have the child process be replaced with the command via 'exec'.   
> Rinse and repeat.
>
> In your case, you might be better off using 'system' instead of  
> 'exec'.  System will take care of
> forking and exec'ing the command for you.
>
>
> Gary Wright
>
>
>

--
Craig Beck

http://www.luckybonza.com
AIM: kreiggers