Hi,

I have finally run into the problem of having tools that require python 3.x on a system that uses python 2.7 standard (Debian Wheezy)

What are the implications of having both installed at the same time?
The tool that I am using is only installing its modules in 2.7, but not in 3.x, how can I fix this without making 3.x default? I would assume that this would break pretty much all the python scripts that are running on the system by default.

Debian is not as uppity as RHEL about python
BUT
you really should KEEP the system default AS THE SYSTEM DEFAULT

then for programs that need settings set for the side by side install of 3.3
use a script to set those in a launcher script

an example on my suse 12 install
i have 3 versions installed
one is a OLD 2.6 for a few old Blender 2.49 plugins i NEED
blender 2.69 uses 3.3 and suse uses 2.7.3

see the mess

well i have to set "PYTHONHOME=" to the OLD 2.6 for the old blender
so it is set in a script used to launch the old version of blender

and reset it back on close
because that setting is in conflict with another python set of tools
"FWTools-linux-x86_64-3.0.6f-usgs"
and that sets all kinds of python variables


but you will want to KEEP the system default as the system default

just change things as needed

Also, in any mixed-versions environment, be careful to keep the libraries of the two versions altogether separate. Most languages have an installed set of libraries that you can reference in your programs, and there can be a lot of C/C++ "voodoo" associated with these things that can be highly dependent upon the APIs exposed by an interpreter. (All of this voodoo is taken care of by the package install process.) So, you want to scrupulously keep these things separate. One library for one version; another library for the other; each installed and maintained using the interpreter version that will be running against it.

The admonition to "not change the system default" is quite crucial since the software that's used to maintain the operating system might conceivably stop working correctly. If you muck-up the package management software, you can find yourself "hoisted on your own petard" (i.e. screwed) rather quickly.