python install command in linux

                                    In RHEL & CENTOS::
Step 1: Open a Terminal and add the repository to your Yum install.

sudo yum install -y https://repo.ius.io/ius-release-el7.rpm

Step 2: Update Yum to finish adding the repository.

sudo yum update

Step 3: Download and install Python.

sudo yum install -y python36u python36u-libs python36u-devel python36u-pip

For verification ::

python3.6 -V

In ubuntu :: 

$ sudo apt-get update
$ sudo apt-get install python3.6