watches files and runs a command when they change

wad.rb

#!/usr/bin/ruby
#
# wad - watch and run
# watches files and runs a command when they change
#
# usage: wad <files> <command>      
#
# example: 
#   ./wad index.html stylesheets/*.sass "sass stylesheets/main.sass stylesheets/main.css; open -g http://127.0.0.1:8000/"

cmd = ARGV.pop

files = {}
loop do
  ARGV.each do |file|
    ctime = File.ctime(file).to_i
 
    if ctime != files[file]
      files[file] = ctime
      puts "# #{cmd}"
      `#{cmd}`
    end
  end
 
  sleep 1
end