syncs /etc/hosts from mydns1 and restart dnsmasq if file has changed

etc_hosts_syncer.sh

#!/bin/bash

# more strict, if something goes wrong, script stops
set -e

workdir=/root/dns_syncer
newhostsfile=$workdir/newhosts

# copy file from primary
scp -q -o LogLevel=QUIET unpriv@mydns1:/etc/hosts $newhostsfile
# this of course needs a functional ssh-key / authorized_key configuration

# if file not exists
if  [ ! -f $newhostsfile ]; then
   exit 0;
fi;

oldhash=($(md5sum /etc/hosts | xargs))
newhash=($(md5sum $newhostsfile | xargs))

if [ "$oldhash" == "$newhash" ]; then
   exit 0;
fi;

cp -f /etc/hosts /etc/hosts.old
mv -f $newhostsfile /etc/hosts

systemctl restart dnsmasq

cat /etc/hosts.old
cat /etc/hosts

echo "done."