bash script to show speed, data remaining and estimated time to completion of Apple OS X FileVault 2 encryption/decryption process

diskutil_encrypt_etd.sh

#!/bin/bash

interval=5 # Sampling time in seconds
volumename="/Volumes/My Passport for Mac/"

total_size=$(diskutil cs info "$volumename" | grep -E "LV Size" | awk '{print $3}')
while [ true ]; do

        first_size=$(diskutil cs info "$volumename" | grep -E "LV Bytes Converted" | awk '{print $4}')
	sleep $interval
	second_size=$(diskutil cs info "$volumename" | grep -E "LV Bytes Converted" | awk '{print $4}')
	speed=$((($second_size-$first_size)/$interval))
	remaining=$((total_size-second_size))

	echo $speed | awk '{ speed = $1 / 1024 / 1024;                  printf  "\rSpeed: %.1f MB/sec"     , speed}'
	echo $remaining | awk '{ remaining = $1 / (1024 * 1024 * 1024); printf " | Remaining: %.4f GB"     ,remaining}'
	echo $remaining $speed | awk '{ ETD = $1 / $2 / 60;             printf " | Time Left: %.1f minutes",ETD }'

done