Bash Cookbook

How to do it...

1. Open a terminal and create the test_ipv4.sh script:

if ping -q -c 1 -W 1 8.8.8.8 >/dev/null; then  echo "IPv4 is up"else  echo "IPv4 is down"fi

2. Now, to test IP connectivity and DNS, create a script called test_ip_dns.sh:

if ping -q -c 1 -W 1 google.com >/dev/nullthen  echo "The network is up"else  echo "The network is down"fi

3. Lastly, create a script called test_web.sh to test web connectivity:

case "$(curl -s --max-time 2 -I http://google.com | sed 's/^[^ ]*  *\([0-9]\).*/\1/; 1q')" in  [23]) echo "HTTP connectivity is up";;  5) echo "The web proxy won't let us through";;  *) echo "The network is down or very slow";;esac