[Discuss] Python script question

[shankar.viswan at gmail.com (Shankar Viswanathan)]

On Wed, Aug 3, 2011 at 10:28 AM, Jerry Feldman <gaf at blu.org> wrote:
> A coworker of mine has a Python script set up as:
> #! $PATH_TO_PYTHON/python
> ... python code
>
> It is not unusual to have commands like this. Mailman does this with
> several of its commands. The issue here is that he needs to use an
> environment variable to call the python interpreter. We certainly can do
> it a messy way:
> #! /bin/bash
> $PATH_TO_PYTHON/python foo.py
>
> But this would require a wrapper script.
>
> Or he can use an explicit path to the python interpreter.
> #! /usr/bin/python
>
> The problem here is that the version of python he uses MUST be
> encapsulated in our company's product.
> #! /mnt/fubar/versionxyz/bin/python
>
> But this will possibly differ with each release of our company's product
> since we maintain a number of releases here. ?Some other solutions is to
> set up symlinks in the local directory.
>
> Any ideas on how to get the loader to expand the environment variable
> after the #!??

At work, we use the 'modules' system to solve this problem:
http://modules.sourceforge.net/

We put the list of modules and versions needed for a project in a
.bashrc file that we customize for each project/customer. You just
have to load the specific .bashrc file for your project, which can
also contain other environment variables in addition to the modules.

The python script can then simply have:
#!/usr/bin/env python
<python code>

This has proved very flexible and versatile system for us when dealing
with multiple tools, both internal and those from external vendors.
You just have to spend some time initially creating the modulefile for
each tool.

Hope this helps,
Shankar