get linux version shell

get_ver.sh

#!/bin/bash
Get_Dist_Name()
{
    if grep -Eqii "CentOS" /etc/issue || grep -Eq "CentOS" /etc/*-release; then
        DISTRO='CentOS'
        PM='yum'
    elif grep -Eqi "Red Hat Enterprise Linux Server" /etc/issue || grep -Eq "Red Hat Enterprise Linux Server" /etc/*-release; then
        DISTRO='RHEL'
        PM='yum'
    elif grep -Eqi "Aliyun" /etc/issue || grep -Eq "Aliyun" /etc/*-release; then
        DISTRO='Aliyun'
        PM='yum'
    elif grep -Eqi "Fedora" /etc/issue || grep -Eq "Fedora" /etc/*-release; then
        DISTRO='Fedora'
        PM='yum'
    elif grep -Eqi "Debian" /etc/issue || grep -Eq "Debian" /etc/*-release; then
        DISTRO='Debian'
        PM='apt'
    elif grep -Eqi "Ubuntu" /etc/issue || grep -Eq "Ubuntu" /etc/*-release; then
        DISTRO='Ubuntu'
        PM='apt'
    elif grep -Eqi "Raspbian" /etc/issue || grep -Eq "Raspbian" /etc/*-release; then
        DISTRO='Raspbian'
        PM='apt'
    else
        DISTRO='unknow'
    fi
    echo $DISTRO;
}

if Get_Dist_Name = "Raspbian"; then
    echo "-------- This is $DISTRO OS !!! --------"
else
    echo "!!!!!!!! Never heard about this OS !!!  !!!!!!!! --------"
fi