(转)Using Python3.5 in Ubuntu

转自：https://www.reddit.com/r/IPython/comments/3lf81w/using_python35_in_ubuntu_trusty/
Note：照这个方案安装python3.5后，很多系统程序用不了了。。因为系统程序用的3.4，所以只能还原系统python版本了：
$ sudo rm /usr/bin/python3
$ sudo mv /usr/bin/python3-old /usr/bin/python3
$ wget https://bootstrap.pypa.io/get-pip.py
$ sudo python3 get-pip.py
$ sudo python get-pip.py
$ sudo pip3 install --upgrade ipython[all]
$ sudo pip install --upgrade ipython[all]
$ sudo rm -rf /usr/local/bin/ipython
$ sudo ln -s /usr/local/bin/ipython2 /usr/local/bin/ipython
# 验证:
$ python --version
$ python3 --version
$ python3.5 --version
$ pip --version
$ pip3 --version
$ ipython
$ ipython3

---

If you haven't already made the switch by installing from the source, and you want to install Python 3.5 system wide, you can use the following steps to upgrade to Python using the fkrull/deadsnakes ppa.

Open a terminal window.

• install Personal Package Archive: ppa:fkrull/deadsnakes
  • sudo add-apt-repository ppa:fkrull/deadsnakes
  • sudo apt-get update
• install the following packages:
  • sudo apt-get install python3.5
  • sudo apt-get install python3.5-dev
  • sudo apt-get install libncurses5-dev
• change python3 link to point to python3.5 instead of python3.4 (/usr/bin/)
  • sudo mv /usr/bin/python3 /usr/bin/python3-old
  • sudo ln -s /usr/bin/python3.5 /usr/bin/python3
• install pip from https://pip.pypa.io/en/stable/installing/
  • wget https://bootstrap.pypa.io/get-pip.py
  • sudo python3 get-pip.py
• install the following with pip3:
  • sudo pip3 install setuptools --upgrade
  • sudo pip3 install ipython[all]
• change the python3 link back
  • sudo rm /usr/bin/python3
  • sudo mv /usr/bin/python3-old /usr/bin/python3
• create python3.5 kernel
  • cp -R ~/.ipython/kernels/python3 ~/.ipython/kernels/python3.5
  • sed -i -- 's/3/3.5/g' ~/.ipython/kernels/python3.5/kernel.json

After your done you can check by creating a Python 3.5 kernel Notebook and entering the following:

import sys
sys.version_info

You should get the following response.

sys.version_info(major=3, minor=5, micro=0, releaselevel='final', serial=0)

*Edit: Reverted the default python3 to python3.4 but created a python3.5 kernel entry for the notebook. The reason for this is that changing the default python3 to python3.5 broke the apt-get updating process.