From: Adam Skobi <dxm997@...>
Date: 2008-10-17T18:29:18+09:00
Subject: Re: Damn you cmd.exe!

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On Fri, Oct 17, 2008 at 10:39 AM, Robert Klemme
<shortcutter@googlemail.com>wrote:

>
>
>  Everything's dandy. It works like a charm. When I try to create an
>> equivalent in win32:
>>
>
> Do you use the native Windows Ruby or cygwin?
>

Native Windows Ruby.


>
>  IO.popen( "cmd.exe", "r+" ) do |cmd|
>>  cmd.puts 'cd'
>>  puts cmd.gets
>> end
>>
>> This thing fails miserably. I can't really pinpoint what is the root cause
>> of it.
>>
>
> Then what does "fails miserably" mean?  Any error messages?
>

Yes i do. It writes in my native language but it translates to something
along the lines: "The process tried to write to a non-existent stream"


>
>
>  I have found here on comp.lang.ruby two solutions. First one:
>>
>> IO.popen( "cmd.exe", "r+" ) do |cmd|
>>  Thread.new(cmd) do |io|
>>    while line = io.gets
>>      puts line
>>    end
>>  end
>>
>
> Yep, that's better anyway (see above).
>
>   cmd.puts "dir"
>>  cmd.puts "cd \\"
>>  cmd.puts "dir"
>>
>>  sleep 3
>> end
>>
>> It works but is sucks badly on many levels as you can see. Other one:
>>
>
> You need to remember the thread and join it at the end of the block if you
> want to make sure that all output from the shell is printed before you leave
> the block.
>


>
>  IO.popen("cmd.exe /c #{single_command}") do | pipe |
>>      pipe.each_line { |line| puts line }
>> end
>>
>> This thing is not so bad but there is a small problem. I want my DSL user
>> to
>> be able to write such simple commands as
>>
>> cd C:\
>> dir
>>
>> The problem is although the both command will run correctly, the change of
>> current directory will be lost between the commands. I can think of some
>> crazy workarounds but I was wondering if there is a way for the cmd.exe to
>> behave normally. Any help would be appreciated.
>>
>
> Well, what is "normal" anyway?  Not all operating systems are similar and
> just because Window's shell behaves differently does not make it abnormal.
> :-)
>


You see, speaking simply, I want to have control on what 'goes in' and what
'goes out'. I don't want to have a background thread reading everything from
cmd.exe  as I wont be able to tell which command produced the output. I
haven't tested it thoroughly but I think it should look like in /bin/bash.
Simple stuff:

shell.puts 'cd /home/me'
shell.puts 'pwd'
puts shell.gets   # /home/me

I am really bedazzled as to why it doesn't seem to work in win32.

-- 
Adam Skobi

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