function checkos(){

if [ -f /etc/redhat-release ];then
OS='CentOS'
elif [ ! -z "`cat /etc/issue | grep bian`" ];then
OS='Debian'
elif [ ! -z "`cat /etc/issue | grep Ubuntu`" ];then
OS='Ubuntu'
else
echo "Not support OS, Please reinstall OS and retry!"
exit 1
fi
}