所以我使用这些说明更新了python：

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

然后

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

然后

./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.
>>>

它工作,但当我关闭终端,并写道
    python -v
它仍然是python 2.7并且仍然在执行使用v3标准库的代码时出错

如何让它像3.5一样工作？