How to check all versions of python installed on osx and centos

Question

I just started setting up a centos server today and noticed that the default version of python on centos is set to 2.6.6. I want to use python 2.7 instead. I googled around and

Answer 1

Find out which version of Python is installed by issuing the command python --version: $ python --version Python 2.7.10

If you see something like this, Python 2.7 is your default version. You can also see if you have Python 3 installed:

$ python3 --version
Python 3.7.2

If you also want to know the path where it is installed, you can issue the command "which" with python and python3:

$ which python
/usr/bin/python

$ which python3
/usr/local/bin/python3