Run a command on a file every time it changes, using inotifywait.

runonfileonchange

#!/bin/bash

if [ $# -ne 2 ]; then
  echo Run a given command on a file when it is modified.
  echo Usage: runonfileonchange command file
  exit 1
fi

while inotifywait -e modify $2; do
  $1 $2
done