Update python on linux 2.7 to 3.5

So I updated python using these instructions:

sudo apt-get install build-essential checkinstall
sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-devlibsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev

then

cd ~/Downloads 
wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tgz
tar -xvf Python-3.5.0.tgz
cd Python-3.5.0

then

./configure
sudo make install



python3.5
Python 3.5.0 (default, Oct  3 2015, 03:16:42) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

and it worked but when I closed terminal, and wrote python -v it is still python 2.7 and still getting errors executing code that use v3+ standard libraries

How to make it working as 3.5?

Answer

You still have Python 2 installed, and the python command is still set up to invoke that version by default. Try running your scripts like this:

python3 yourscriptname.py

In /usr/bin/, “python” is actually a symlink to python2.7. If you’d rather not have to type the 3 at the end whenever you use python, change that symlink to point to python3 instead. Then python will run Python 3.5 and you can use python2.7 or just python2 to run Python 2.7 scripts.

EDIT: Alternatively, you could put alias python=python3 in your ~/.bashrc file to do the same thing, but without needing root access and for your user account only.