Intall Python 3 on Ubuntu

0. Install related packages:
sudo apt-get install build-essential libncursesw5-dev libreadline5-dev libssl-dev libgdbm-dev libbz2-dev libc6-dev libsqlite3-dev tk-dev g++ gcc

1. Download the file to /tmp:
cd /tmp
wget http://www.python.org/ftp/python/3.1.1/Python-3.1.1.tgz

2. Unzip the tar zip file:
tar xzvf Python-3.1.1.tgz

3. Run configuration command ./configure
* In case you encounter some problem, install build-essential

4. make (optional)

5. Install the program to system:
sudo make install