Installing Python 2.6 in CentOS 5 (or RHEL5)

CentOS 5 uses python 2.4, and replacing it is not really on
option since yum and other core packages depend on it. My solution is to
compile 2.6 and use /opt or /usr/local for the prefix. I also create a virtualenv
with the new python executable, so when I’m in the environment 2.6
becomes the default python. It also isolates all my python libraries for
a given project. Most of this article is actually distribution
agnostic, and the yum build requirement install will likely work on
other versions of CentOS and other RedHat derivatives like Fedora.

Install Build Requirements

Run the following command as root (or with sudo) to install gcc and the development libraries used by python:

yum install gcc gdbm-devel readline-devel ncurses-devel zlib-devel \
bzip2-devel sqlite-devel db4-devel openssl-devel tk-devel bluez-libs-devel

Compile Python

Download and unpack the source tarball for your version of choice. For example:

VERSION=2.6.1
mkdir ~/src
cd ~/src
wget http://python.org/ftp/python/$VERSION/Python-$VERSION.tar.bz2 tar xjf Python-$VERSION.tar.bz2
rm Python-$VERSION.tar.bz2
cd Python-$VERSION
./configure --enable-ipv6 --prefix=/opt
make
sudo make install

Run ./configure –help for more configure options.

If you plan to install multiple versions of python to the same
prefix, use “sudo make altinstall” instead of “make install” for the
versions you want installed as python2.6 etc, and “make install” for the
default version you want installed as simply python. See the README for
more details.

After running the make command you will see a list of modules that
were not built. If you installed all of the devel libraries listed
above, the only missing modules should be bsddb185 and sunaudiodev. You
probably don’t need these – bsddb185 is the old version of the berkely
db module, and sunaduiodev is for solaris. On x86_64 db and imageop may
also be in the list, but looking at the setup.py, it looks like this is
normal.

Install setuptools

Download setuptools
– get the egg if it’s available for your version of python, otherwise
get the tarball. In either case prepend PREFIX/bin to your path, where
PREFIX is what you passed to configure when building python (/opt in my
example). Then either run the egg as a shell script or unpack the
tarball and run “python setup.py install”. Here’s an example for
setuptools 0.6c9 and python 2.6:

wget http://pypi.python.org/packages/2.6/s/setuptools/setuptools-0.6c9-py2.6.egg#md5=ca37b1ff16fa2ede6e19383e7b59245a sudo PATH=/opt/bin:$PATH sh setuptools-0.6c9-py2.6.egg
rm setuptools-0.6c9-py2.6.egg

Install virtualenv and virtualenvwrapper

sudo /opt/bin/easy_install virtualenv
sudo /opt/bin/easy_install virtualenvwrapper

Install More Packages (Optional)

If you plan on using other modules in all your projects, and don’t
need different versions, you can install them once in the main
site-packages dir for your new python install. Just make sure to use the
full path to easy_install (or prepend /opt/bin to the PATH when running
eggs or python setup.py), otherwise they will be installed for the
system python (2.4 in CentOS 5).

Setup virtualenvwrapper

UPDATED 4-9: Thanks Brian for the feedback. Hopefully this is more clear.

Create a directory to store your virtual environments:

mkdir ~/.virtualenvs

Add the following lines to your bashrc (~/.bashrc):

export PATH=/opt/bin:$PATH
export WORKON_HOME=$HOME/.virtualenvs
source /opt/bin/virtualenvwrapper_bashrc

If you used a prefix other than /opt (e.g. /usr/local) when
installing python, then change the PATH line and the source line
accordingly. This also assumes you are using bash. I’m not sure how to
set up virtualenvwrapper for other shells.

The PATH line will actually make python 2.6 your default interpreter
for login sessions. If this is undesirable you may be able to copy
virtualenv to some other location already in your path, and it will
should still use the appropriate version of python. Be careful if you
have virtualenv installed under your main system python – virtual
environments created with other version will be tied to that version of
python.

New login sessions will automatically source ~/.bashrc and have
support for virtualenvwrapper – to update your currently running shell,
source it explicitly:

source ~/.bashrc

IMPORTANT: you should use “#!/usr/bin/env python” for your scripts
instead of “#!/path/to/python” to make them more portable and work in
different virtualenv.

More documentation: virtualenvwrapper, Doug Hellmann’s original virtualenvwrapper article, virtualenv

Create a virtualenv (using virtualenvwrapper)

Choose a name for your new environment. I will use NewEnv as a placeholder. You can create new environments with mkvirtualenv:

mkvirtualenv NewEnv

This command will also automatically activate the new environment. To
activate NewEnv in another shell, use the “workon” command:

workon NewEnv

Running workon without any arguments will give you a list of all the
virtualenv’s you’ve created. Here are some common packages you may want
to easy_install into your new virtualenv. Note that you don’t need to
use sudo to install stuff into your virtualenv:

workon NewEnv
easy_install MySQL-python
easy_install twisted
easy_install egenix-mx-base

Install PostgreSQL and psycopg2

Centos 5 has postgres 8.1. To install a 8.3, setup the PostgreSQL yum repository,
remove any old versions (but not -libs), and yum install
postgresql-devel. Note that you may need to remove nfs-utils to avoid a
libevent conflict (or maybe find an updated nfs-utils if you really need
it).

sudo yum erase nfs-utils
sudo yum erase postgresql postgresql-devel
sudo rpm -ivh http://yum.pgsqlrpms.org/reporpms/8.3/pgdg-centos-8.3-6.noarch.rpm sudo yum update
sudo yum install postgresql-devel

workon NewEnv
easy_install psycopg2