From: "J.Hawkesworth" <J.Hawkesworth@...>
Date: 2003-05-28T01:56:41+09:00
Subject: Re: system calls

Don't know if this helps but I recall that in perl you have to divide by
256 to get the real return value.  (Tried to test here but running under
Windows and therefore have no 'fork' to eat really_cool_system with).

All the best,

Jon

-----Original Message-----
From: Brian Candler [mailto:B.Candler@pobox.com]
Sent: 27 May 2003 17:48
To: ruby-talk ML
Subject: Re: system calls


On Tue, May 27, 2003 at 10:24:50PM +0900, mgarriss wrote:
> so I can get the standard output from a system call:
> 
>   s = `date`
> 
> and I can get the return value:
> 
>   system( "date" )
> 
> and I have no idea how to get the standard error:
> 
>   ???
> 
> but what I really want is all three, like:
> 
>   out, err, ret = really_cool_system( "date" )

This is almost what you want, except that the exit code is wrong and I
don't
know how to fix it:

require 'open3'
module Kernel
  private
  def really_cool_system(*args)
    inp, out, err = Open3.popen3(*args)
    ret1 = ret2 = nil
    t1 = Thread.new do
      inp.close
    end
    t2 = Thread.new do
      ret1 = out.read
      out.close
    end
    t3 = Thread.new do
      ret2 = err.read
      err.close
    end
    t1.join
    t2.join
    t3.join
    return ret1, ret2, $?
  end
end

irb(main):024:0> really_cool_system("ls","/dev/null","/dev/foo")
=> ["/dev/null\n", "ls: /dev/foo: No such file or directory\n", 65280]

Regards,

Brian.


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