How do I run Python code as a script? [duplicate]

I need help running python in ubuntu

I can run python without a problem in my terminal but when I create a .py file I can't get it to run.

How it works (examples for python2, for python3, replace all occurrences of python by python3):

1. python /path/to/script.py
   • works if file is either executable or not
   • shebang (#!/usr/bin/env python) in the head of the script is good practice, but not needed
2. /path/to/script.py
   • works if script is executable
   • shebang is needed (#!/usr/bin/env python)
3. script.py
   • works if script is in $PATH
   • script needs to be executable
   • filename needs to have extension
   • shebang is needed (#!/usr/bin/env python)
4. script
   • works if script is in $PATH
   • script needs to be executable
   • filename should have no extension
   • shebang is needed (#!/usr/bin/env python)

A bit more information: precedence of command, shebang or extension?

The shell can get its information on how to run a script from two sources (in order of precedence):

• The language information in the command: python <script>
• The shebang, in the first line of the script: #!/usr/bin/env python

The language extension however does not play a role(!).

A few examples:

1. A bash script, correct (language) information in the command, incorrect shebang, incorrect extension:

   #!/usr/bin/env python
   echo 'Monkey eats banana'
   

   ran with:

   $ sh /path/to/script.py
   > Monkey eats banana
   

   runs correctly, the information in the command takes precedence over both the shebang and the extension.

2. An (executable) python script, ran with incorrect extension, but a correct shebang:

   #!/usr/bin/env/python
   print "Monkey eats banana"
   

   ran with:

   $ /path/to/script.sh
   > Monkey eats banana
   

   runs correctly, the information in the shebang takes precedence over the extension.

3. An (executable) python script, with a correct extension, but without shebang (and without language information in the command):

   print "Monkey"
   

   Ran with the command:

   $ /path/to/script.py
   > Error: no such file "Monkey"
   

   does not run correctly, in spite of the language extension!

Probably you need to make it executable.

chmod +x /path/to/your/file.py

To run a python script, use python:

python script.py