/usr/bin/env python

[Craig Treleaven]

At 12:10 AM +1100 12/17/12, Joshua Root wrote:
>On 2012-12-16 19:46 , vincent habchi wrote:
>>  Folks,
>>
>>  Some scripts of a port I'm trying to set up use #!/usr/bin/env 
>>python, which seem to always point to Apple's python. Which 
>>environment variable have I to change so that 'env' will return a 
>>MacPorts python instead?
>
>There is no environment variable that will help here; 'python' is not
>guaranteed to be present in ${prefix}/bin.
>
>The reason /usr/bin/env is used in the shebang line here is that the
>interpreter for a script must be an absolute path, but the author
>doesn't know where python will be on the user's system. The env command
>is for altering the environment, but is used without setting any
>variables, and is thus a noop that gets around the absolute path
>requirement. Only PATH has any effect on which python is found.

For my edification...I see this all the time with Python but never 
Perl.  Is there some reason the former needs it and the latter 
doesn't?  Do other scripting languages require the env 'trick'?

Craig