Show a file read process counter for a specific file and program

lame-pv

#!/bin/bash -e

pid=${1?No PID given}
file=${2?No File given}
size=$(stat --printf %s $file)

cd /proc/$pid/fd
for fd in *
do
  if [ "$file" == "$(readlink $fd)" ]; then
    break
  fi
done

cd ..

pos=$(awk -v ORS='' '/pos/{print $2}' fdinfo/$fd)

echo $(echo "scale=3; $pos * 100 / $size" | bc)%