Automatically Managing Network Routes on Raspberry Pi for Reliable Internet Connectivity

check_internet.sh

#!/bin/bash

# IP for Google's DNS server used for testing connectivity
TEST_IP=8.8.8.8

# Ping TEST_IP using wlan0. If successful, ensure routing through wlan0
if ping -I wlan0 -c 4 $TEST_IP > /dev/null; then
  echo "Internet connectivity is available through wlan0. Adjusting routes..."
  # Get the default gateway IP for wlan0
  GATEWAY_IP=$(ip route show default via | grep wlan0 | awk '{print $3}')
  # Delete the default route for eth0
  sudo ip route del default dev eth0
  # Add a new default route via wlan0 if not already set
  if ! ip route show default via $GATEWAY_IP dev wlan0 | grep -q 'default via'; then
    sudo ip route add default via $GATEWAY_IP dev wlan0
  fi
else
  echo "No Internet connectivity available through wlan0."
fi