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 found that 2.6.6 is used by system tools such as YUM so I should not tamper with it. Then I opened up a terminal on my mac and found that I had python 2.6.8 and 2.7.5 and 3.3.3 installed. Sorry for the long story. In short I just want to know how to lookup all the version of python installed on centos so I don’t accidentally install it twice.

The more easy way its by executing the next command:

ls -ls /usr/bin/python*

Output look like this:

/usr/bin/python           /usr/bin/python2.7        /usr/bin/pythonw
/usr/bin/python-config    /usr/bin/python2.7-config /usr/bin/pythonw2.7

we can directly use this to see all the pythons installed both by current user and the root by the following:
whereis python

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

Here is a cleaner way to show them (technically without symbolic links). This includes python2 and python3 installs:

ls -1 /usr/bin/python* | grep '.*[2-3]\(.[0-9]\+\)\?$'

Where grep filters the output of ls that that has that numeric pattern at the end ($).

Or using find:

find /usr/bin/python* ! -type l

Which shows all the different (!) of symbolic link type (-type l).

Use,

yum list installed

command to find the packages you installed.

As someone mentioned in a comment, you can use which python if it is supported by CentOS. Another command that could work is whereis python. In the event neither of these work, you can start the Python interpreter, and it will show you the version, or you could look in /usr/bin for the Python files (python, python3 etc).

COMMAND: python --version && python3 --version

OUTPUT:

Python 2.7.10
Python 3.7.1

ALIAS COMMAND: pyver

OUTPUT:

Python 2.7.10
Python 3.7.1

You can make an alias like “pyver” in your .bashrc file or else using a text accelerator like AText maybe.

It depends on your default version of python setup. You can query by Python Version:

python3 --version //to check which version of python3 is installed on your computer
python2 --version // to check which version of python2 is installed on your computer
python --version // it shows your default Python installed version.

ls -l /usr/bin/python* & ls -l /usr/local/bin/python*

compgen -c python | grep -P '^python\d'

This lists some other python things too, But hey, You can identify all python versions among them.

Sift through the output of this script.

sudo find / -name 'python*' -type f  -exec du -h {}  + | sort -r -h ~/Documents/python_locations.txt

I would add to @nurealam siddiq answer,

python --version // it shows your default Python installed version.

python2 --version // to check which version of python2 is installed 

python3 --version //to check which version of python3 is installed 

python3.X --version // to further check which python3.X is installed