python-version.md

What Python version is that?!

• Check the Python version on the command line: --version, -V, -VV
• Check the Python version in a script: using sys and platform
  • The version string displayed at start: sys.version
  • A named tuple of version number components: sys.version_info
  • A function returning a string: platform.python_version()
  • A tuple of version number components: platform.python_version_tuple()

Defensive coding

To ensure a script runs with a minimal version requirement of the Python interpreter one can use an assertion. More levels (micro, releaselevel, etc) can be added to the tuple, if necessary.

assert sys.version_info >= (2, 5)

Examples

• The installed Python version can be determined from the command line using --version, -V, and -VV parameters.

  $ python --version

  Python 3.7.8
  

  Or

  $ python -V

  Python 3.7.8
  

  Or

  $ python -VV

  Python 3.7.8 (tags/v3.7.8:4b47a5b6ba, Jun 28 2020, 08:53:46) [MSC v.1916 64 bit (AMD64)]
  

• To get the version number from a script, sys and platform modules are useful.

  • The string displayed when the interactive interpreter is started is sys.version

    import sys
    print(sys.version)

    3.7.8 (tags/v3.7.8:4b47a5b6ba, Jun 28 2020, 08:53:46) [MSC v.1916 64 bit (AMD64)]
    

  • The version information is also available as a named tuple sys.version_info

    import sys
    print(sys.version_info)

    sys.version_info(major=3, minor=7, micro=8, releaselevel='final', serial=0)
    

  • There is also a function platform.python_version() returning the version string.

    import platform
    print(platform.python_version())

    3.7.8
    

  • The latter information is also available as function which returns a tuple.

    import platform
    print(platform.python_version_tuple())

    ('3', '7', '8') 
    

  • There is a wealth of other information related to the Python build available in platform.

— Oliver Frolovs, 2020