Debian 8 x64 (jessie)
python –version
sudo apt-get update

bash: sudo: command not found.
su –
apt-get install sudo

sudo apt-get update
dpkg -l python*

sudo apt-get install build-essential -y
sudo apt-get install libncurses5-dev libncursesw5-dev libreadline6-dev -y
sudo apt-get install libdb5.3-dev libgdbm-dev libsqlite3-dev libssl-dev -y
sudo apt-get install libbz2-dev libexpat1-dev liblzma-dev zlib1g-dev -y

sudo apt-get install libssl-dev openssl

wget https://www.python.org/ftp/python/3.5.1/Python-3.5.1.tgz
tar zxvf Python-3.5.1.tgz
cd Python-3.5.1
./configure –prefix=/usr/local/python35
make all
sudo make install

安装好后把 python3 添加到PATH里，打开~/.bashrc 文件，在最后添加：
$ vi ~/.bashrc
添加
export PATH=$PATH:/usr/local/python35/bin

echo “export PATH=$PATH:/usr/local/python35/bin” >> ~/.bashrc
cat ~/.bashrc
保存后：
source ~/.bashrc

python3 –version

sudo rm /usr/bin/python /usr/bin/python2
sudo ln -s /usr/local/python35/bin/python3.5 /usr/bin/python
sudo ln -s /usr/local/python35/bin/pip3 /usr/bin/pip
sudo pip install –upgrade pip
http://www.moguf.com/post/setuppython3