Update MAC address using ethtool

mac_update.sh

#!/bin/bash

PATTERN='^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$'

print_usage() {
    echo "Need NIC name"
    echo "usage: $0 eth0 00:11:22:33:44:55"
}

if [ -z $1 ]; then
    print_usage $0
    exit 1
else
    dev=$1
fi

if [ -z $2 ]; then
    print_usage $0
    exit 1
else
    mac=$2
fi

# Check MAC address
ethtool $dev > /dev/null
if [[ $? -ne 0 ]]; then
    echo "Invalid NIC name $dev"
    print_usage $0
    exit 1
fi

# Check MAC address
if [[ ! "$mac" =~ $PATTERN ]]; then
    echo "Invalid mac address"
    print_usage $0
    exit 1
fi

# Update MAC address
for ((i=0; i<6; i++))
do
    tmp=`expr $i + 1`
    val=`echo $mac | awk -F ':' -v "v=$tmp" '{print $v}'`

    ethtool -E $dev magic 0x10d38086 offset $i value 0x$val
done

echo "Update MAC address complete."