simple "how much longer" bash script (inspired by waiting on a disk to zero out with DD, watching "892044574720 bytes (892 GB, 831 GiB) copied, 9013 s, 99.0 MB/s"

arewethereyet.sh

if [ $# -lt 3 ]
  then echo "expecting 3 numaric prams: # goal size in GB, # amount complete in GB, # speed in MB/s"
       exit 1
fi

goal=$1
sofar=$3
speed=$2

onegbmb=1024

echo "goal $1gb, so far $2gb, speed $3MB/s"
remain=$(($goal-$sofar))
remMB=$(($remain*$onegbmb))
echo "remaining $remain gb ($remMB mb)"
remTime=$(($remMB/$speed))
echo "at $speed MB/s, $remTime seconds to go"
remMins=$(($remTime/60))
echo "... or $remMins minutes"