runtime location discovery

[Jeff Shannon]

In article <mailman.1017453478.23509.python-list at python.org>, 
geoff at gerrietts.net says...
 
> The other night, I tried to put in a chunk of code that allowed the
> program to be executed from an arbitrary location (like a user's home
> directory) without previously knowing where we were installed
> (allowing the app to be installed wherever it seems most natural to
> the system administrator).
> 
> The code I wrote did this:
>     root_location = os.path.dirname(sys.argv[0])

This also suffers from the problem that, if you cd to the 
directory that the script is in and then run it, sys.argv[0] will 
not contain path information.

One solution that I've used, is to look at the __file__ attribute 
of a module that I've imported, like so:

import MyModule
installdir = os.path.dirname(MyModule.__file__)

This will tell you the directory that MyModule.py is located in, 
which you can arrange to be the directory that you're interested 
in.  ;)  Be aware, though, that in your original script (with 
__name__ == '__main__'), the __file__ attribute is undefined 
(which is why I grab it from a module, instead of directly in the 
executing script).

-- 

Jeff Shannon
Technician/Programmer
Credit International