Option 1: Call the interpreter

• For Python 2: python <filename>.py
• For Python 3: python3 <filename>.py

Option 2: Let the script call the interpreter

1. Make sure the first line of your file has #!/usr/bin/env python.
2. Make it executable - chmod +x <filename>.py.
3. And run it as ./<filename>.py

Method one: some as Windows (not the best option)

Tell the file-manager to open files ending in .py in python /usr/bin/python3 (note the slash at the start). Then double click it.

Method two (not the best option)

Open a shell and type python3 «script name»

Method three (the preferred method)

• Add #!/usr/bin/python3 as the first line of the script.
• Make the file executable chmod +x «script name» (or right click in your file-manager).

side note:

With this method it is better to remove the .py, as it is not needed, and leaks the implementation: All callers of the script need to know the programming language.

You have to add a shebang. A shebang is the first line of the file. Its what the system is looking for in order to execute a file.

It should look like that :

Copy#!/usr/bin/env python

or the real path

Copy#!/usr/bin/python

You should also check the file have the right to be execute. chmod +x file.py

As Fabian said, take a look to Wikipedia : Wikipedia - Shebang (en)