Conflicting versions of python in ubuntu

Question

So i had python 2.7.2 on my server and i needed to update it to python 2.7.3. So i've tried to remove the 2.7.2 version and then install the new one using the sources. I wasn't able to remove the 2.7.2 version cause the system uses it to run crucial services on server, so i installed the 2.7.3 version in hope that after that i would be able to remove the old version. Still i cant remove the old version, although i'm able to execute the python 2.7.3 when i install any module i cant import it. I added the path to sys.path and i started finding the module but importing it causes another errors.

My python executes the /usr/local/bin/python which is the 2.7.3 version where the problems are. If i try to execute python like this /usr/bin/python it executes the old version and everything works fine there, i can import the new installed modules.

So what can i do to make python 2.7.3 work?

I've searched a lot of tutorials and tried things like add the library in .pth files on python and i started finding the modules but when importing it i get errors like this:

>>> import numpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/numpy/__init__.py", line 137, in <module>
    import add_newdocs
  File "/usr/local/lib/python2.7/dist-packages/numpy/add_newdocs.py", line 9, in <module>
    from numpy.lib import add_newdoc
  File "/usr/local/lib/python2.7/dist-packages/numpy/lib/__init__.py", line 4, in <module>
    from type_check import *
  File "/usr/local/lib/python2.7/dist-packages/numpy/lib/type_check.py", line 8, in <module>
    import numpy.core.numeric as _nx
  File "/usr/local/lib/python2.7/dist-packages/numpy/core/__init__.py", line 5, in <module>
    import multiarray
ImportError: /usr/local/lib/python2.7/dist-packages/numpy/core/multiarray.so: undefined symbol: PyUnicodeUCS4_AsUnicodeEscapeString

Thanks for the help

EDIT PROBLEM SOLvED

So to solve the missing import modules i created a .pth file under /usr/local/lib/python2.7/site-packages/ with the directories where the python modules are and the python starts to find them. To fix the comptability problems you can install python from sources and specify the unicode doing ./configure --enable-unicode

more information here

Answer 1

Do not EVER mess with system python, EVER.

What you should do is install python 2.7.3 with a --prefix into your home directory, then use virtualenv -p /home/myuser/path/to/python.

In any case, using virtualenv to run your own application is almost always a good idea, as it avoids polluting the system package directories with libraries you use in your own applications.

Answer 2

It looks like the modules you've installed were built against your old version of Python, or at least a version incompatible with your newer installation. The import error you're seeing at the bottom is the numpy module searching for a symbol that is not in your build of 2.7.3. There is further information here.

If possible, it's usually way easier to upgrade Python with a package manager. That way, if anything on your system depends on Python, but does not need exactly 2.7.2, then Python can be easily upgraded without disturbing anything. I'm guessing that either your server doesn't have a newer version of Python available and you can't add new repositories, or you don't have access to a package manager. If using packages is possible, I would go ahead and remove what you've built from source (the command should be 'make clean' if Python uses GNU Make).

If that isn't an option, then there should be a way to compile Python, but not install it into system directories. Then you could add a symlink for users, and make sure that symlink has precedence in their path.