vprogress

#!/bin/bash
#(C) Kirils Solovjovs, 2021
scale=60
scaletext="min"


precisehit=1
target=0
mmm='^[0-9]+$'
if [[ "$1" =~ $mmm ]] ; then
 target="$1"
 precisehit=0
 shift
elif [[ "${1::-1}" =~ $mmm ]] && [[ "${1: -1}" == "!" ]] ; then
 target="${1::-1}"
 precisehit=1
 shift
fi

n=5
command="$@"

before="$(echo "$command" | /bin/bash | head -1 | tr -dc 0-9.- | cut -d . -f 1)"
[ "$before" == "" ] && before=0
started="$before"
while true; do
 echo  ... measuring ${n}s ...
 sleep $n
 after="$(echo "$command" | /bin/bash | head -1 | tr -dc 0-9.- | cut -d . -f 1)"
 [ "$after" == "" ] && after=0
 clear

 difference=$(( $after - $before ))
 speed=$((100000 * $difference*$scale/$n ))
 printf %+.2f\ items/"$scaletext"\\n "$((speed))e-5"

 [ "$difference" -gt "$target" ] && [ "$speed" -lt 0 ] && remaining="NONE"

 remaining=$(( $target - $after ))
 if [ "$speed" -eq 0 ]; then
  eta="NONE"
 else
  eta=$(( 100000 * 10 * $remaining / $speed ))
  [ "$eta" -lt 0 ] && eta="NONE"
 fi

 [ "$difference" -lt 0 ] && difference=$(( -($difference) ))
 if [ "$difference" -ne 0 ]; then #if there is no change we dont know if its slow or not
  if [ "$difference" -le 20 ]; then #these numbers ...
   n=$((n+5))
  elif [ "$difference" -gt 40 ]; then # .. will need some math
   n=$((n-1))
   [ "$n" -le 0 ] && n=1
  fi
 fi

 [ "$speed" -lt 0 ] && remaining=$(( -($remaining) ))

 echo Items: $after/$target
 if [ "$speed" -ne 0 ]; then
  echo -n "To go: $remaining items, "
  if [ "$eta" == "NONE" ]; then
   echo - $scaletext
  else
   printf %.1f\ "$scaletext"\\n "$((eta))e-1"
  fi
 else
  echo To go: -stalled-
 fi

# echo Started with: $started

 if [ "$remaining" -eq 0 ]; then
  echo
  echo Exact target reached.
  exit 0
 fi

 if [ "$remaining" -le 0 -a "$precisehit" == "0" -a "$speed" -ne 0 ]; then
  echo
  echo Target reached.
  exit 0
 fi

 before="$after"
done