From: Mohit Sindhwani <mo_mail@...>
Date: 2007-09-21T03:21:11+09:00
Subject: Re: Interactive System calls within Ruby Script

ZyLo wrote:
> I'm not sure whether this is possible or not, but I know that Ruby
> allows you to make system calls in many different ways, and I
> generally use:
>
> system "echo Hello"
>
> or something when I want to call outside of the script.  What I would
> like to know is if it is possible to make these system calls
> interactive?  For instance, I was toying with directory manipulation
> using system "cd .." system "pwd", etc., and I noticed that no matter
> what the call, Ruby will always return to the same directory on the
> system "pwd" command.
>
> I was wondering if it is possible to send multiple commands so you
> could be a bit more interactive with it?  I know there are libraries
> out there to do this for me, but I am looking at this more from the
> standpoint that I'm not planning on using this ability for directory
> manipulation.
>
> Another thing I was wondering is whether you can get output from the
> terminal on system calls.  I tried somethign like this:
>
> system "pwd"
> gets directorystring
> puts directorystring
>
> Only my script doesn't get the input at all, and hangs(expecting an
> input I assume).
>
> How can you usefully use system for calling functions if it doesn't
> remember state(directory, for instance), or allow you to get back
> terminal information?
>
>
>   
I'm sure you'll get back much better answers than mine but just to get 
you started, this is what I have been doing.  When needing to change 
directory within my script, I usually do it from the ruby equivalent.  
Also, as for getting back what the command you called sent to its 
stdout, use back ticks...

for example,

output_from_cmd = `myotherprogram.exe`

this sends the stdout of the myotherprogram.exe to the variable 
output_from_cmd within your script.

Hope this helps some.

Cheers,
Mohit.
9/21/2007 | 2:20 AM.

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