Question

I have a problem which is caused by our encapsulated design. Up till now lots of our scripts were written in bash and as a result the #!/bin/bash was always simple.

However now that we are rewriting our scripts in python that is a bit more difficult. We deliver a specific version of python (to avoid version differences in client installed environments from breaking our implementation). Because the specific version of python lives in a installed directory structure I need to route to it.

However I don’t think the #! statement can accept environment variables from the shell that executes the file(tried and got a bad interpreter).

eg:

in foo.py I have #!$dirloc/wherepythonlives/python

In the bash shell I executed the file and got bad interpreter.
Is there a way of sneaking an environment variable into that #! line?

Or will I have to depend on an explicit path? We want to support multiple versions of our software (which may mean multiple python versions) on one environment so I was hoping to somehow keep Python’s !# statement inside the directory level we install into.

Answer 1

A common way to do this is to use the env program:

#!/usr/bin/env python

This will cause env to look along the PATH environment for a binary called python.