From: "Philip W." <likelink@...>
Date: 2007-05-13T00:07:56+09:00
Subject: Re: Writing A Ruby Shell

Peter Cooper wrote:
> On 5/12/07, Philip W. <likelink@jetsoftdev.com> wrote:
>>
>> Hello all,
>>
>>     I'm writing a Ruby shell for Ubuntu Linux 7.04. I would like my
>> shell to take commands from the user, run the command, output the result
>> to the command line, and log the result in a file. But I am having
>> trouble getting the Ruby shell to output the result to the command line,
>> and log the command. I've tried everything I can think of - using the
>> backticks method (``), exec(), system(), and IO.popen, strange
>> combinations of the mentioned and eval(), but nothing satisfies both of
>> my requirements. Sometimes the shell will output the command result to
>> the shell, but it won't log it. Sometimes it will log the command
>> result, but it won't output it to the shell. Sometimes it does one or
>> both things, but it only outputs or logs some of the command result. I
>> would appreciate any help that I could get on ways to make this work.
>
>
> Perhaps I'm missing your ultimate point here, but one major problem I 
> see is
> that you can't really just slurp out the "results" for, say, a text 
> editor
> (such as vi or pico) or any sort of interactive script. If your shell
> doesn't allow access to those sort of programs, it wouldn't be 
> particularly
> useful (unless you envision a use for a shell that only allows you to
> perform the most basic of commands).
>
> Is it necessary to log all output? Generally "system" will give you the
> closest (but not exact) match to what happens when you normally run a
> program under a shell, but of course that doesn't return the output of 
> the
> command you run.. although it does let you get into interactive apps, 
> etc.
>
>> From what I can tell, the main problem you appear to be running into 
>> is that
> some programs are not just sending output to stdout, or are redefining 
> what
> stdout is. This is why shells often do lots of freaky things to make sure
> output ends up where it should.
>
> Cheers,
> Peter Cooper
> http://www.rubyinside.com/
>
I would like to log all output, but if it came down to it I could do 
without logging all output. What I'm shooting for with my shell in terms 
of interactiveness is the closest match to running a command under a 
regular shell.