On Aug 31, 2006, at 2:11 PM, Tom Allison wrote:

>
> grrr.... that's not what the man pages, books, and everything else  
> say...
>
> On 8/31/2006, "Logan Capaldo" <logancapaldo / gmail.com> wrote:
>
>>
>> On Aug 30, 2006, at 11:49 PM, Tom Allison wrote:
>>
>>> I'm trying to run 'ruby -d foo.rb' and the d is either ignored or I
>>> don't understand how it works.  The code just runs as if there is
>>> no -d option.
>>>
>>> Does this require something at compile time of Ruby that I might
>>> have overlooked?
>>>
>>
>> Maybe you wanted ruby -rdebug -d foo.rb ?
>>
>
  Well -d sets $DEBUG to true. -rdebug loads debug.rb which is the  
included debugger. The two are actually almost orthogonal most of the  
time you can do just ruby -rdebug foo.rb.

As far as what the man page says:
-d
      --debug        Turns on debug mode.  $DEBUG will be set to true.

It doesn't say that it will also run a debugger ;)