ping exercise in plain bash

output

$ ./pinger.sh "google.com facebook.com zuehlke.com"
average ping time for zuehlke.com: 63.600 ms
average ping time for facebook.com: 61.161 ms
average ping time for google.com: 61.953 ms

pinger.sh

#!/bin/bash

function ping_time() {
	ping -c1 $1 | grep 'time=' | cut -d ' ' -f 7 | cut -d '=' -f 2
}

function calc() {
	bc <<< "scale=3;$1 $2 $3"
}

function avg_ping_time() {
	local total=0
	local num_pings=6
	for i in $(seq 1 $num_pings); do
		latency=$(ping_time $1)
		total=$(calc $total '+' $latency)
		sleep 10
	done
	echo "average ping time for $1: $(calc $total '/' $num_pings) ms"
}

HOSTS=${1:-localhost}

# spawn background processes for each host (so they run in parallel) and wait
for host in $HOSTS; do
	avg_ping_time $host &
done
wait