net-test.sh

#!/usr/bin/env bash
#
#?
# Net Test - Monitors network connectivity for downtime.
#
# Usage: net-test.sh 
#
# Attempts to connect to an internet service to verify internet connectivity 
# every second. Prints the status of this check in the format:
#
#	<Unix Time> <Internet Connectivity> <Fallback Number> <Ping Time>
#
# Where <Internet Connectivity> is a 0 or a 1. And <Fallback Number> is the 
# index of the site in test_sites which the internet connectivity status was 
# determined with.
#
# Arguments
#	--no-header: Makes script not print sites header
#?

# List of sites to test internet connectivity with
test_sites=("1.1.1.1" "8.8.8.8" "google.com" "wikipedia.com")
test_interval=1

# Arguments
op_no_header="false"
while [ ! -z "$1" ]; do
	key="$1"
	shift

	case "$key" in
		--no-header)
			op_no_header="true"
			;;
		*)
			echo "Error: unknown argument \"$key\"" >&2
			exit 1
			;;
	esac
done

# Print site names
if [ "$op_no_header" != "true" ]; then
	for site in "${test_sites[@]}"; do
		echo "#$site"
	done
fi

# Check
while true; do
	current_time="$(date +%s)"
	internet_conn=0
	fallback_num=0
	ping_time="-1"

	# Try each test site until one succeeds
	for site in "${test_sites[@]}"; do
		ping_time_out=$((ping -c 1 "$site" | tail -1 | awk '{print $4}' | cut -d '/' -f 2) 2> /dev/null)
		if [ ! -z "$ping_time_out" ]; then
			internet_conn=1
			ping_time="$ping_time_out"
			break
		fi
		fallback_num=$(("$fallback_num" + 1))
	done

	# Record
	echo "$current_time $internet_conn $fallback_num $ping_time"

	sleep "$test_interval"
done