What's the difference between /usr/lib/python and /usr/lib64/python?

Question

I was using ubuntu.

I found that many Python libraries installed went in both /usr/lib/python and /usr/lib64/python.

When I print a module object, the module path showed that the module lived in /usr/lib/python.

Why do we need the /usr/lib64/python directory then? What's the difference between these two directories?

BTW

Some package management script and egg-info that lived in both directories are actually links to packages in /usr/share.

Most Python modules are just links, but the so files are not.

Answer 1

Debian (and probably it's derivatives, most notably ubuntu) uses /usr/lib for both architectures. /usr/lib64 is provided as a symlink to /usr/lib for compatibility reasons. Some newer applications might be looking in /usr/lib64 for libraries, while some legacy code might be using /usr/lib. Other distributions can provide multi-architecture support, having 32 bit and 64 bit libraries installed on the same machine, which would then be placed in /usr/lib and /usr/lib64 accordingly. An example of this would be Arch Linux, as described here.

Some python libraries are platform independent anyway (.py code), so it makes sense to create a single package for both architecture to minimize maintenance effort. This package would then install itself in both lib and lib64, or, as you pointed out already, in one single directory that is symlinked to from both lib and lib64.