getmyip

#!/bin/bash

if [ "$(id -u)" != "0" ] 
then
    echo "Only root can run this."
    exit 2
fi
MYIP=$(hostname -I)

# only run this on the 192.168.0 network
GO=FALSE
for I in $MYIP
do
    TMP=$(echo $I | cut -f1-3 -d.)
    if [ $TMP == 192.168.0 ]
    then
        GO=TRUE
        break
    fi
done
[ $GO == "FALSE" ] && exit 1

# lets check to see if we can ping extender 
# (the other router at 192.168.0.7)
ping -c4 extender > /dev/null 2>&1
#ping -c4 blah > /dev/null 2>&1

# if we get a 0 return value, we can assume we are home.
if [ $? -ne 0 ]
then
    echo not at home
    exit 1
fi

# get our extern IP address
IP=$(curl icanhazip.com 2> /dev/null)

# we do this a couple of times so have put it in a function.
# update the /etc/hosts with our external IP address.
add_ip() {
    echo "$1 wombat" >> /etc/hosts
}


#echo $IP

# test to see if there is already an entry for wombat in the hosts file.
if grep wombat /etc/hosts > /dev/null
then
    # grab the ip from the hosts file and check to see if it matches the
    # newly reported one.
    OLD=$(grep wombat /etc/hosts | gawk '{print $1}')
    echo "found current entry: $OLD"
    if [ $OLD == $IP ]
    then
        # the newly report IP is the same as the one in the hosts file
        # not need to do anything.
        echo "Current entry is correct"
        exit 0
    else
        # the newly report IP is not the same as the one we have. 
        # lets fix it.
        echo "Correcting hosts file"
        DATE=$(date '+%y-%m-%d_%H-%M')
        echo "$DATE $OLD" >> ~michael/wombat.old
        cp /etc/hosts /tmp/
        grep -v wombat /tmp/hosts > /etc/hosts
        add_ip $IP
    fi
else
    # No entry is found in the host file. We need to add it.
    echo "Adding to hosts"
    add_ip $IP
fi