From: Scheming Commie <ired@...>
Date: 2006-08-02T12:15:10+09:00
Subject: How to auto-locate interpreter image

On Sat, 15 Jul 2006 21:06:25 +0000, Just Another Victim of the Ambient
Morality wrote:
>     I'm pretty sure the "#!" line is meaningless on Windows and the shell 
> doesn't even bother looking for it.  Indeed, it always struck me a little 
> weird that every script knows exactly where the interpreter image is.  What 
> if it were to move?  All your scripts will suddenly break!  An annoying, 
> albeit, unlikely scenario...

#!/usr/bin/env perl
#!/usr/bin/env ruby
.. etc

env finds the interpreter wherever it is and runs it, as you'd expect. 

A neat trick, I don't know why it isn't used, well, universally.

Of course it relies on env being in /usr/bin but, that changes less
(never) than where particular interpreters are.