The usual approach is to download the source and build and install locally (but not directly in virtualenv), and then create a new virtualenv using that local Python install. On some systems, it may be possible to download and install a prebuilt python, rather than building from source.

Pre-requisites:

1. sudo easy_install virtualenv
2. sudo pip install virtualenvwrapper

Installing virtualenv with Python2.6:

1. You could manually download, build and install another version of Python to /usr/local or another location.

2. If it’s another location other than /usr/local, add it to your PATH.

3. Reload your shell to pick up the updated PATH.

4. From this point on, you should be able to call the following 2 python binaries from your shell python2.5 and python2.6

5. Create a new instance of virtualenv with python2.6:

   mkvirtualenv --python=python2.6 yournewenv

No, but you can install an isolated Python build (such as ActivePython) under your $HOME directory.

This approach is the fastest, and doesn’t require you to compile Python yourself.

(as a bonus, you also get to use ActiveState’s binary package manager)

This procedure installs Python2.7 anywhere and eliminates any absolute path references within your env folder (managed by virtualenv). Even virtualenv isn’t installed absolutely.

Thus, theoretically, you can drop the top level directory into a tarball, distribute, and run anything configured within the tarball on a machine that doesn’t have Python (or any dependencies) installed.

Contact me with any questions. This is just part of an ongoing, larger project I am engineering. Now, for the drop…

1. Set up environment folders.

   $ mkdir env
   $ mkdir pyenv
   $ mkdir dep
   

2. Get Python-2.7.3, and virtualenv without any form of root OS installation.

   $ cd dep
   $ wget http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz
   $ wget https://raw.github.com/pypa/virtualenv/master/virtualenv.py
   

3. Extract and install Python-2.7.3 into the pyenv dir. make clean is optional if you are doing this a 2nd, 3rd, Nth time…

   $ tar -xzvf Python-2.7.3.tgz
   $ cd Python-2.7.3
   $ make clean
   $ ./configure --prefix=/path/to/pyenv
   $ make && make install
   $ cd ../../
   $ ls
   dep    env    pyenv
   

4. Create your virtualenv

   $ dep/virtualenv.py --python=/path/to/pyenv/bin/python --verbose env
   

5. Fix the symlink to python2.7 within env/include/

   $ ls -l env/include/
   $ cd !$
   $ rm python2.7
   $ ln -s ../../pyenv/include/python2.7 python2.7
   $ cd ../../
   

6. Fix the remaining python symlinks in env. You’ll have to delete the symbolically linked directories and recreate them, as above. Also, here’s the syntax to force in-place symbolic link creation.

   $ ls -l env/lib/python2.7/
   $ cd !$
   $ ln -sf ../../../pyenv/lib/python2.7/UserDict.py UserDict.py
   [...repeat until all symbolic links are relative...]
   $ cd ../../../
   

7. Test

   $ python --version
   Python 2.7.1
   $ source env/bin/activate
   (env)
   $ python --version
   Python 2.7.3
   

Aloha.

Although the question specifically describes installing 2.6, I would like to add some importants points to the excellent answers above in case someone comes across this. For the record, my case was that I was trying to install 2.7 on an ubuntu 10.04 box.

First, my motivation towards the methods described in all the answers here is that installing Python from deadsnake’s ppa’s has been a total failure. So building a local Python is the way to go.

Having tried so, I thought relying to the default installation of pip (with sudo apt-get install pip) would be adequate. This unfortunately is wrong. It turned out that I was getting all shorts of nasty issues and eventually not being able to create a virtualenv.

Therefore, I highly recommend to install pip locally with wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py && python get-pip.py --user. This related question gave me this hint.

Now if this doesn’t work, make sure that libssl-dev for Ubuntu or openssl-dev for CentOS is installed. Install them with apt-get or yum and then re-build Python (no need to remove anything if already installed, do so on top). get-pip complains about that, you can check so by running import ssl on a py shell.

Last, don’t forget to declare .local/bin and local python to path, check with which pip and which python.

I’m using virtualenvwrapper and don’t want to modify $PATH, here’s how:

$ which python3
/usr/local/bin/python3

$ mkvirtualenv --python=/usr/local/bin/python3 env_name

I have not found suitable answer, so here goes my take, which builds upon @toszter answer, but does not use system Python (and you may know, it is not always good idea to install setuptools and virtualenv at system level when dealing with many Python configurations):

#!/bin/sh

mkdir python_ve
cd python_ve

MYROOT=`pwd`
mkdir env pyenv dep

cd ${MYROOT}/dep
wget https://pypi.python.org/packages/source/s/setuptools/setuptools-15.2.tar.gz#md5=a9028a9794fc7ae02320d32e2d7e12ee
wget https://raw.github.com/pypa/virtualenv/master/virtualenv.py
wget https://www.python.org/ftp/python/2.7.9/Python-2.7.9.tar.xz
xz -d Python-2.7.9.tar.xz

cd ${MYROOT}/pyenv
tar xf ../dep/Python-2.7.9.tar
cd Python-2.7.9
./configure --prefix=${MYROOT}/pyenv && make -j 4 && make install

cd ${MYROOT}/pyenv

tar xzf ../dep/setuptools-15.2.tar.gz

cd ${MYROOT}

pyenv/bin/python dep/virtualenv.py --no-setuptools --python=${MYROOT}/pyenv/bin/python --verbose env
env/bin/python pyenv/setuptools-15.2/setup.py install
env/bin/easy_install pip

echo "virtualenv in ${MYROOT}/env"

The trick of breaking chicken-egg problem here is to make virtualenv without setuptools first, because it otherwise fails (pip can not be found). It may be possible to install pip / wheel directly, but somehow easy_install was the first thing which came to my mind. Also, the script can be improved by factoring out concrete versions.

NB. Using xz in the script.

Now a days, the easiest way I found to have a more updated version of Python is to install it via conda into a conda environment.

Install conda(you may need a virtualenv for this)

pip install conda

Installing a new Python version inside a conda environent

I’m adding this answer here because no manual download is needed. conda will do that for you.

Now create an environment for the Python version you want. In this example I will use 3.5.2, because it it the latest version at this time of writing (Aug 2016).

conda create -n py35 python=3.5.2

Will create a environment for conda to install packages

To activate this environment(I’m assuming linux otherwise check the conda docs):

source activate py35

Now install what you need either via pip or conda in the environemnt(conda has better binary package support).

conda install <package_name>

You may use pyenv.

There are a lot of different versions anaconda, jython, pypy and so on…

https://github.com/yyuu/pyenv

Installation as simple as pyenv install 3.2.6

pyenv install --list
Available versions:
  2.1.3
  2.2.3
  2.3.7
  2.4
  2.4.1
  2.4.2
  2.4.3
  2.4.4
  2.4.5
  2.4.6
  2.5
  2.5.1
  2.5.2
  2.5.3
  2.5.4
  2.5.5
  2.5.6
  2.6.6

…

First of all, Thank you DTing for awesome answer. It’s pretty much perfect.

For those who are suffering from not having GCC access in shared hosting, Go for ActivePython instead of normal python like Scott Stafford mentioned. Here are the commands for that.

wget http://downloads.activestate.com/ActivePython/releases/2.7.13.2713/ActivePython-2.7.13.2713-linux-x86_64-glibc-2.3.6-401785.tar.gz

tar -zxvf ActivePython-2.7.13.2713-linux-x86_64-glibc-2.3.6-401785.tar.gz

cd ActivePython-2.7.13.2713-linux-x86_64-glibc-2.3.6-401785

./install.sh

It will ask you path to python directory. Enter

../../.localpython

Just replace above as Step 1 in DTing’s answer and go ahead with Step 2 after that. Please note that ActivePython package URL may change with new release. You can always get new URL from here : http://www.activestate.com/activepython/downloads

Based on URL you need to change the name of tar and cd command based on file received.

Full guide with pyenv

If pyenv is not installed then install it with pyenv-installer:

$ curl https://pyenv.run | bash

To use any custom python version, e.g. 3.5.6 use the following:

pyenv install 3.5.6
pyenv virtualenv 3.5.6 NAME_OF_YOUR_ENV
cd YOUR_PROJECT_PATH
pyenv local NAME_OF_YOUR_ENV

virtualenv –python=".localpython/bin/python2.7" env