From: Tobias Reif <tobiasreif@...>
Date: 2002-05-29T20:37:20+09:00
Subject: Re: OS independent scripts, system calls on Windows and Linux

Dossy wrote:


> Unlike Unix, where "date" is a real command that can be executed
> by another program, in DOS the "date" command is a shell builtin,
> part of COMMAND.COM (or CMD.EXE, or whatever DOS shell you're
> running).  So, this isn't a bug in Ruby at all, it's a misunderstanding
> of yours how things are supposed to work.


I enter commands at the "DOS prompt". Now if it's possible, I'd like to 
have a mechanism in Ruby to which I can pass the exact same commandline, 
and they get executed, just as in the commandline. If it's possible, I'd 
like the mechanism to automatically handle the differences behind the 
scenes, so that I can pass it ver, date, whatever, just as in the 
commandline window, and it just works.

BTW, here's my current .bat file in case anyone's interested in what I'm 
doing:
([OT] does anyone know how I can stop the batch script as soon as one 
command returned an error? I just begun learning (ugly) .bat scripting.)

-----
@echo off
rem
rem should run on Windows ME/98/95,
rem  also XP and 2000/NT
rem  (ran on: ME, )
rem
rem "rem" lines are comments (remark, remove)
rem
rem in the project directory, run
rem all
rem
rem the source XML always gets validated
rem to validate all XML documents, run
rem all -va
rem (validate all)
rem for validation with remote DTDs one must be online
rem
rem
echo validating source XML:
domcount svg-links.xml
rem
echo source to xhtml:
java com.icl.saxon.StyleSheet -o links.xhtml svg-links.xml links2xhtml.xslt
rem
if not "%1" == "-va" goto afterXhtmlVal
echo validating xhtml:
domcount links.xhtml
:afterXhtmlVal
rem
echo source to dot:
java com.icl.saxon.StyleSheet -o links.dot svg-links.xml links2dot.xslt
rem
echo dot to svg:
dot -Tsvg -o links.svg links.dot
rem
if not "%1" == "-va" goto afterSvgVal
echo validating SVG:
domcount links.svg
:afterSvgVal
rem

-----


> Try this:
> 
> C:\WINDOWS\COMMAND>ver

[...]

> C:\WINDOWS\COMMAND>ruby -e 'puts `mem`'
> C:\WINDOWS\COMMAND>ruby -e 'puts system("mem")'


all work


> See, backticks (`) and #system both simply search the PATH
> environment variable for an executable that you've named.

> If it doesn't find it (like in the case of "date" or "ver"
> which are both shell builtins and not standalone executables)
> ... well ... it won't find it, and not be able to execute
> it.


C:\WINDOWS>ruby -e "puts `dot -V`"
dot version 1.8.4 (Thu Apr 18 15:08:04 EDT 2002)
C:\WINDOWS>ruby -e "puts `domcount`"
Usage:
     DOMCount [options] <XML file | List file>

both are on the path and work OK; but:

C:\WINDOWS>ruby -e "puts `java -version`"
-e:1: command not found: java -version

C:\WINDOWS>java -version
java version "1.3.0_01"
[...]

I added Java to the path, it works, but not from Ruby, and the Java path 
is not visible in path.
Windows seem to be a mess. Unless there's an error above; what can I do 
to call Java from Ruby? Would it be possible for Ruby to find Java, by 
looking in the right places, or asking the "DOS shell", which does know 
where it is?

Tobi

-- 
http://www.pinkjuice.com/