meh

copy_status.sh

#!/bin/bash
## ./script path1 path2

src=$1
dst=$2
function percentage {
  jq -n "$(du -s $1 | cut -f1)/$(du -s $2 | cut -f1)*100"
}

cat last_check || :

result_1=$(percentage)
sleep 1
result_2=$(percentage)

touch check_diff
jq -n "$result_2 - $result_1" >> check_diff

avg=$(awk '{s+=$1}END{print (NR?s/NR:"0")}' RS=" " check_diff)
secs=$(jq -n "(100-$result_2)/$avg|floor")

printf 'Completion: %f%%\nETA: %dh:%dm:%ds\n' $result_2 $(($secs/3600)) $(($secs%3600/60)) $(($secs%60)) > last_check

if [ "$(cat check_diff |wc -l)" -gt 50 ]; then
  echo "$(tail -25 check_diff)" > check_diff
fi