How to tell a Python program where a shared library is?

[Donn Cave]

Quoth "Edward C. Jones" <edcjones at erols.com>:
| Suppose I have a shared library, say "mymodule.so". How do I tell a Python
| program where "mymodule.so" is? If necessary I can change the PATH environment
| variable. How is this done?

If python is going to import mymodule directly ("import my"), then
you can give python the location (just the directory, not the file
name) via PYTHONPATH

   $ PYTHONPATH=$mypath python
or
   $ PYTHONPATH=$mypath export PYTHONPATH     (innumerable variations)
   $ python

or push it into sys.path from the program itself -

   import sys
   sys.path.insert(0, mypath)

Try this to see both sides at work:

   PYTHONPATH=$mypath python -c 'import sys; print sys.path'

Now, don't do this on an NFS mounted filesystem.  You'll see that
this includes the current working directory.  If you let python
load a .so over NFS, it will be hard to reliably update that module.
You can change the file, python will still see the old one.

	Donn Cave, donn at u.washington.edu