yum -y install lsyncd

 vi /etc/lsyncd.conf

settings  {
 logfile = "/var/log/lsyncd.log",
 statusFile = "/var/log/lsyncd.stat",
 statusInterval = 2,
}
sync {
 default.rsync,
 source="/home/ning/cloud/",
 target="/home/ning/www/"
}

sync {
 default.rsync,
 source="/home/ning/www/",
 target="/home/ning/cloud/"
}