Tuesday, June 14, 2016

Upgrade Python on Oracle Linux

When deploying (currently) an Oracle Linux instance on the Oracle public compute cloud you will most likely get python version 2.6.6. The deployment version of Oracle Linux will provide you with Oracle Linux 6.6 configured in the manner as Oracle has prepared it for cloud deployment. Which is not that different from what you might install yourself.

The below screenshot from the Oracle compute cloud shows the version we will be using in this example.

As stated, this version will be shipping Python 2.6.6. In some cases you do want to upgrade your python version. We will upgrade Python in this example from Python 2.6.6 to a Python 2.7.6 version. Python is also shipping in a Python 3.x.x version, however, some changes to Python have been made which might render existing python code written under Python 2.x.x. unusable. For this reason we will stick with Python 2.7.6 while also perserving the Python 2.6.6 version on the system.

In esscence this is not making it a upgrade which will replace the old version, it is rather a Python 2.7.6 installation where we make Python 2.7.6 the default version instead of the Python 2.6.6 version.

Preparing the system
We will be compiling Python so we have to ensure we have the right development and build tooling installed. This can be done with yum by doing a group install and a install of a number of other packages as shown below.

yum groupinstall "Development tools"

yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel

This ensures your Linux environment will have all the needed packages to do the compilation of Python 2.7.6

Downloading and compiling
We will be downloading the source code and compiling it into a workable version. A couple of things to keep in mind during the compilation are that we "need" to extent the configure command with the below to ensure the path in compiled into the executable during compilation.  LDFLAGS="-Wl,-rpath /usr/local/lib"

The following steps are needed to download, configure and build Python 2.7.6 into you systems:

cd /tmp
wget http://python.org/ftp/python/2.7.6/Python-2.7.6.tar.xz
tar xf Python-2.7.6.tar.xz
cd Python-2.7.6
./configure --prefix=/usr/local --enable-unicode=ucs4 --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"
make altinstall

With this done you should now have Python 2.7.6 installed on your system

Making Python 2.7.6 default
As we have installed Python 2.7.6 installed next to Python 2.6.6 the default version is still 2.6.6. you can check it in the same fashion as shown below

[root@tensor-0 bin]# which python
[root@tensor-0 bin]# python --version
Python 2.6.6
[root@tensor-0 bin]# 

As you can see python is found in /usr/bin/ and is currently version 2.6.6 while we would like Python 2.7.6 to be the default version.

You can achieve this by doing the following:
  • Rename /usr/bin/python to /usr/bin/python to /usr/bin/python2.6
  • softlink /usr/local/bin/python2.7 to /usr/bin/python (as shown below)

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

This should ensure that you now have Python version 2.7.6 as the prime version when calling it. You can again check this by doing a python --version command which now should show 2.7.6 instead of 2.6.6

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