Upgrade python without breaking yum

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Upgrade python without breaking yum

I recently installed Python 2.7.3 on a CentOS machine by compiling from source. Python 2.7.3 is installed at /opt/python2.7 and when I installed it I just changed /usr/bin/python to point to the new version. This apparently is wrong though because when I did it it broke yum. I would get the following.
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

No module named yum

Please install a package which provides this module, or
verify that the module is installed correctly.

It’s possible that the above module doesn’t match the
current version of Python, which is:
2.7.3 (default, May 15 2012, 17:45:42)
[GCC 4.4.4 20100726 (Red Hat 4.4.4-13)]

If you cannot solve this problem yourself, please go to
the yum faq at:
http://yum.baseurl.org/wiki/Faq

I changed /usr/bin/python to point back to the python 2.6.6 but now 2.6.6 is the default version of python. Any idea how to fix this?

Solutions/Answers:

Solution 1:

I have written a quick guide on how to install the latest versions of Python 2 and Python 3 on CentOS 6 and CentOS 7. It currently covers Python 2.7.13 and Python 3.6.0.

You are not supposed to change the system version of Python because it will break the system (as you found out). Installing other versions works fine as long as you leave the original system version alone. This can be accomplished by using a custom prefix (for example /usr/local) when running configure, and using make altinstall (instead of the normal make install) when installing your build of Python.

Having multiple versions of Python available is usually not a big problem as long as you remember to type the full name including the version number (for example “python2.7” or “pip2.7”). If you do all your Python work from a virtualenv the versioning is handled for you, so make sure you install and use virtualenv!

Solution 2:

vim `which yum`
modify #/usr/bin/python to #/usr/bin/python2.4

Solution 3:

Put /opt/python2.7/bin in your PATH environment variable in front of /usr/bin…or just get used to typing python2.7.

Solution 4:

pythonz, an active fork of pythonbrew, makes this a breeze. You can install a version with:

# pythonz install 2.7.3

Then set up a symlink with:

# ln -s /usr/local/pythonz/pythons/CPython-2.7.3/bin/python2.7 /usr/local/bin/python2.7
# python2.7 --version
Python 2.7.3

Solution 5:

ln -s /usr/local/bin/python2.7 /usr/bin/python

Solution 6:

If you want to try out rpm packages, you can install
binary packages based on the newest Fedora rpms, but recompiled
for RHEL6/CentOS6/ScientificLinux-6 on:

http://www.jur-linux.org/download/el-updates/6/

best regards,

Florian La Roche

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