How to Compile Python from Source

Here we are going compile python from source. I assume you have a clean installation of Debian testing. Here are few packages required for compilation.

apt-get -y install build-essential zlib1g-dev libbz2-dev \
    libncurses5-dev libreadline-gplv2-dev libsqlite3-dev \
    libssl-dev libgdbm-dev

Once above installation is complete, download python source code from here: http://www.python.org/ftp/python/. Suppose you choose to download python 2.5.2.

cd /usr/local/src
wget http://www.python.org/ftp/python/2.5.2/Python-2.5.2.tar.bz2
tar xjf Python-2.5.2.tar.bz2
cd Python-2.5.2

Since most of libraries in Debian moved from /usr/lib to /usr/lib/i386-linux-gnu we need create symbolic links in old location so the build scripts can find them all. This is far easier than specify a valid library location for each case. Here are links:

ln -s /usr/lib/i386-linux-gnu/libssl.so \
    /usr/lib/libssl.so
ln -s /usr/lib/i386-linux-gnu/libcrypt.so \
    /usr/lib/libcrypt.so
ln -s /usr/lib/i386-linux-gnu/libcrypto.so  \
    /usr/lib/libcrypto.so
ln -s /usr/lib/i386-linux-gnu/libbz2.so  \
    /usr/lib/libbz2.so
ln -s /usr/lib/i386-linux-gnu/libgdbm.so  \
    /usr/lib/libgdbm.so
ln -s /usr/lib/i386-linux-gnu/libcurses.so  \
    /usr/lib/libcurses.so
ln -s /usr/lib/i386-linux-gnu/libz.so  \
    /usr/lib/libz.so
ln -s /usr/lib/i386-linux-gnu/libsqlite3.so  \
    /usr/lib/libsqlite3.so

Compilation

Before we start compile we need to configure it first. You can run it with all defaults (this will install python to /usr/local/).

./configure

Or you can specify some other location:

./configure --prefix=/usr/local

The configuration process take few seconds. Next issue make command to actually compile it (this may take few minutes). The -s option prints warning only and -j 2 utilizes 2 CPU cores during the compilation).

make -s -j 2

You can optionally test it before installing with:

make test

or run specific tests of your interest:

./python Lib/test/test_hashlib.py

Install

make install

Python executable should be located at /usr/local/bin/python2.5.

Extra Packages

While python is perfectly working at this moment you might need install some extra packages (e.g. virtualenv) with easy_install.

wget -O - -q http://python-distribute.org/distribute_setup.py | python2.5
easy_install-2.5 virtualenv

This way you can install as many python versions as you like.

Troubleshooting

While working with some third party package (e.g. django) you got the following error:

ImportError: ...undefined symbol: PyUnicodeUCS2_Replace

There reason is described here. You have to re-configure the python:

./configure --enable-unicode=ucs4

and build/install it again.