How to get the Python version

Shows how to get the Python version from a running Python program and an execution example. There are multiple ways to get the version:

1. sys.version_info
2. platform.python_version_tuple()
3. six

Method 1: sys.version_info

sys.version_info stores the Python version of the execution environment. For Python less than 2.7 / 3.0, the type is tuple, and for 2.7 / 3.1 and later, the type is named tuple.

Execution example

python2.5

>>> import sys
>>> sys.version_info
(2, 5, 2, 'final', 0)

python2.7

>>> import sys
>>> sys.version_info
sys.version_info(major=2, minor=7, micro=12, releaselevel='final', serial=0)

python3.5

>>> import sys
>>> sys.version_info
sys.version_info(major=3, minor=5, micro=2, releaselevel='final', serial=0)

Reference [28.1. sys — System-specific parameters and functions — Python 2.7.11 documentation] (https://docs.python.org/2.7/library/sys.html)

sys.version_info

A tuple containing the five components of the version number: major, minor, micro, releaselevel, and serial. All values except releaselevel are integers; the release level is 'alpha', 'beta', 'candidate', or 'final'. The version_info value corresponding to the Python version 2.0 is (2, 0, 0, 'final', 0). The components can also be accessed by name, so sys.version_info[0] is equivalent to sys.version_info.major and so on.

New in version 2.0.

Changed in version 2.7: Added named component attributes

Method 2: platform.python_version_tuple ()

platform.python_version_tuple () gets the version number information as tuple regardless of the Python version.

Execution example

>>> import platform
>>> platform.python_version_tuple()
('2', '7', '14')

python3.6

>>> import platform
>>> platform.python_version_tuple()
('3', '6', '4')

Reference 15.15. platform — Access to underlying platform’s identifying data — Python 2.7.11 documentation

New in version 2.3.

platform.python_version_tuple()

Returns the Python version as tuple (major, minor, patchlevel) of strings.

Note that unlike the Python sys.version, the returned value will always include the patchlevel (it defaults to '0').

Method 3: six

six can be used to determine whether Python 2 or Python 3 (and Python 3.4 or higher can be determined).

Execution example

Python2.7

>>> import six
>>> six.PY2
True
>>> six.PY3
False
>>> six.PY34
False

Python3.6

>>> import six
>>> six.PY2
False
>>> six.PY3
True
>>> six.PY34
True

The internal implementation uses the above sys.version_info.

six.py

# Useful for very coarse version differentiation.
PY2 = sys.version_info[0] == 2
PY3 = sys.version_info[0] == 3
PY34 = sys.version_info[0:2] >= (3, 4)

Bonus: Python version determination on Shell Script

One liner to get the major version of Python

Python2/3

$ pymajorver=$(python -c "from __future__ import print_function; import sys; print(sys.version_info[0])")
$ echo $pymajorver
3

You can also use it in the case statement as follows:

python

case $(python -c "from __future__ import print_function; import sys; print(sys.version_info[0])") in
    "2") echo "Python2 !!" ;;
    "3") echo "Python3 !!" ;;
    *) echo "Unknown Python version" ;;
esac

One liner to get major / minor version of Python

Supports both Python 2/3

Python2.7

$ python -c "from __future__ import print_function; import sys; print('{}{}'.format(*sys.version_info[0:2]))"
27

Python 3 only

Python3.6

$ pyversion=$(python -c "import sys; print('{}{}'.format(*sys.version_info[0:2]))")
$ echo $pyversion
36