systemname=`uname -a`
echo $systemname

ubuntu1804="18.04."
ubuntu1604="16.04."
result=$(echo $systemname | grep "${ubuntu1804}")
if [[ "$result" != "" ]]
then
    echo "ubuntu 18.04"
fi

result=$(echo $systemname | grep "${ubuntu1604}")
if [[ "$result" != "" ]]
then
    echo "ubuntu 16.04"
fi