From: "Ara.T.Howard" <ara.t.howard@...>
Date: 2005-11-24T02:34:45+09:00
Subject: Re: getting stdout and stderr for system calls on windows

On Thu, 24 Nov 2005, Damphyr wrote:

> OK, I'm stuck with a pretty problem:
> I need to drive a build process using make (dmake) from my scripts and I
> want to capture stdout and stderr as well as the return value from dmake.
> Normally I would do it using Daniel Berger's win32-popen3, but I have a
> Windows Installer Ruby with VC++6.0 which nastily gives me a segfault
> (properly documented in the README, but still a segfault :) ).  Recompiling
> Ruby is a no-no and changing VC compiler also a no-no.
>
> Now, does anyone have a quick solution for me?  Is there anyway to call say:
>
> system 'echo blabla'
>
> and to redirect stdout and stderr used by system? (I guess not).
> Any help is appreciated.
> I am aware of
>
> IO.popen("dmake target 2>&1") {|f|
>    output = f.read
>    exitcode = Process.waitpid2(f.pid)[1]
>  }
> and is currently my best choice, although I would like to split stderr and 
> stdout.
>
> Cheers,
> V.-

i was working on this at one point:

   harp:~ > cat a.rb
   class Redirector
     require "tempfile"
     attr_accessor "ruby"
     def initialize
       @ruby = "ruby"
       @script = tempfile
       @script.write <<-ruby
         stdout, stderr = ARGV.shift, ARGV.shift
         File::unlink out rescue nil
         File::unlink err rescue nil
         STDOUT.reopen(open(stdout,"w"))
         STDERR.reopen(open(stderr,"w"))
         system(ARGV.join(' '))
       ruby
       @script.close
     end
     def run command, redirects = {}
       stdout = redirects.values_at("stdout", :stdout, "o", :o, 1).compact.first
       tout = nil
       unless stdout
         tout = tempfile
         stdout = tout.path
       end
       stderr = redirects.values_at("stderr", :stderr, "e", :e, 2).compact.first
       terr = nil
       unless stderr
         terr = tempfile
         stderr = terr.path
       end
       system "#{ @ruby } #{ @script.path } #{ stdout } #{ stderr } #{ command }"
       ret = IO::read(stdout), IO::read(stderr), $?.exitstatus
       tout.close! if tout
       terr.close! if terr
       ret
     end
     def tempfile
       Tempfile::new(Process::pid.to_s << rand.to_s)
     end
   end

   redirector = Redirector::new

   stdout, stderr, exitstatus = redirector.run "echo 42"
   p [stdout, stderr, exitstatus]

   redirector.run "echo 42", 1 => "out", 2 => "err"
   p [IO::read("out"), IO::read("err")]


   harp:~ > ruby a.rb
   ["42\n", "", 0]
   ["42\n", ""]

regards.

-a
-- 
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| ara [dot] t [dot] howard [at] noaa [dot] gov
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| comes from the desire for oneself to be happy.
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