How to check OS version in bash?

Question

linux

Good morning. Please tell me how to check the name of the distribution and its version in the .sh file.
For example: If the name of the distribution is Debian and its version is 7, then .sh should download one file.
And if the name of the distribution is CentOS and its version is 7, then the second file should be downloaded.

Answer 1

cat /etc/*-release
This is a small bash script.

#!/bin/bash 
RELISE=`cat /etc/*-release| tr "\n" " "`

for name in 'CENTOS' 'UBUNTU' 'DEBIAN'
do
        echo $RELISE | grep -i -q $name && echo "OS name is $name"
done