The 3.0 version of Python is often called Python 3000, or Py3k for short. This is a major upgrade compared to earlier versions of Python. In order not to bring too much burden, Python 3.0 was not designed with backward compatibility in mind.
Python3 interpreter syntax
On Linux/Unix systems, the default python version is generally 2.x. We can install python3.x in the /usr/local/python3 directory. After the installation is complete, we can add the path /usr/local/python3/bin to the environment variable of your Linux/Unix operating system, so that you can enter the following command through the shell terminal to start Python3.
Python3 interpreter example
$ PATH=$PATH:/usr/local/python3/bin/python3 #Set environment variables $ python3 --versionPython 3.4.0