script for updating Mac Addresses on cloned VM of RHEL/CentOS6

gistfile1.txt

#!/bin/sh
UdevRules=/etc/udev/rules.d/70-persistent-net.rules

mv -f ${UdevRules} ${UdevRules}.old
udevadm trigger --subsystem-match="net" --action add 
sleep 5

if [ ! -e "${UdevRules}" ]; then
  exit 1
fi

for devFile in /etc/sysconfig/network-scripts/ifcfg-eth*
do
        # main
        devName=${devFile##*-}
        MacAddr=`grep ${devName} ${UdevRules} | awk '{print $4}' | sed -e 's/.*"\(.*\)",.*/\1/;'`
        grep HWADDR "${devFile}" >/dev/null 2>&1
        if [ $? -eq 0 ]; then
                sed -e "s/^HWADDR.*/HWADDR=${MacAddr}/" ${devFile} > /tmp/ifcfg.$$
                cp /tmp/ifcfg.$$ ${devFile}
                rm -f /tmp/ifcfg.$$
                
        else
                printf "HWADDR=${MacAddr}\n" >> ${devFile}
        fi
done