From: Quintus <sutniuq@...>
Date: 2010-09-13T05:21:04+09:00
Subject: Re: Wait on external program?

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Am 12.09.2010 19:26, schrieb Larry Jones:
> Marvin,
> 
> Thanks for the suggestion; however, I don’t understand how this will 
> force Ruby to wait until the external process is complete.
> 
> Are you suggesting some sort of while.. loop waiting for the variable to 
> change?
> 
> The external process is not Ruby code but a windows application.
> 
> Thanks,
> Larry

The backtick method (yeah, that'a a method, see
http://www.ruby-doc.org/ruby-1.9/classes/Kernel.html#M002609 ) executes
the command you pass, waits for it to finish and captures the output
emmited by the command. I'm on Linux Ubuntu at the moment, but this
example should explain it:

irb(main):001:0> str = `sleep 2; echo hello`
=> "hello\n"
irb(main):002:0>

I use sleep to simulate a long-running operation (well, 2 seconds
lasting ;-) ) followed by outputting hello. The "hello" gets captured by
the backticks method and I assign it to the variable str.

The Kernel#system method is similar to the backticks (it waits for the
process to finish as well), but it doesn't capture the output.

Vale,
Marvin
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