Add failover Debian

installFailoverIp.sh

#!/bin/sh
display_usage() { 
    echo "This script must be run with super-user privileges." 
    echo -e "\nUsage:\n$0 ip [interface] \n" 
    echo -e "\nExample:\n$0 192.168.0.1 eth1 \n"
} 
# if less than one argument supplied, display usage 
if [  $# -le 0 ] 
then 
    display_usage
    exit 1
fi 
 
# check whether user had supplied -h or --help . If yes display usage 
if [[ ( $# == "--help") ||  $# == "-h" ]] 
then 
    display_usage
exit 0
	fi 
 
# display usage if the script is not run as root user 
if [[ $USER != "root" ]]; then 
    echo "This script must be run as root!" 
    exit 1
fi 

FAILOVER_IP=$1
NET_DEV=$2
if [  $# -le 1 ] 
then 
    NET_DEV="eth0"
fi

ALIAS_NUMBER=$(command grep -e "iface[ \t]*${NET_DEV}:" '/etc/network/interfaces' \
    | command wc --lines)
command echo "auto ${NET_DEV}:${ALIAS_NUMBER}
iface ${NET_DEV}:${ALIAS_NUMBER} inet static
  address ${FAILOVER_IP}
  netmask 255.255.255.255
  broadcast ${FAILOVER_IP}
" >> '/etc/network/interfaces'
command ifup ${NET_DEV}:${ALIAS_NUMBER}