watchfs.rb

#!/usr/bin/ruby
 
# This script watches modifications on the given directory, using the new
# FSEvents API in Leopard.
 
 
# This is a modification from the original watch script provided by Apple's Developer Package
# usage: watch [path/to/watch] [bash cmd to execute]
# by Julius Eckert
 
require 'osx/foundation'
OSX.require_framework '/System/Library/Frameworks/CoreServices.framework/Frameworks/CarbonCore.framework'
include OSX
 
def die(s)
  $stderr.puts s
  exit 1
end
 
@@last_exec = nil
def exec_cmd(path)
  # execute given command only every 3 seconds
  if (@@last_exec.nil? || Time.new > @@last_exec + 3)
    # 2>&1 redirect STDERR into terminal output
    puts `#{ARGV[1]} #{path} 2>&1`
    @@last_exec = Time.new
  end
end
 
die "Usage: #{__FILE__} <path> <command>" unless ARGV.size == 2
exec_cmd(".")
 
fsevents_cb = proc do |stream, ctx, numEvents, paths, marks, eventIDs|
  paths.regard_as('*')
  numEvents.times do |n|
    puts "[watch] ==> #{paths[n]}"
    exec_cmd(paths[n])
  end
end
 
path = ARGV.first
stream = FSEventStreamCreate(
  KCFAllocatorDefault,
  fsevents_cb,
  nil,
  [path],
  KFSEventStreamEventIdSinceNow,
  1.0,
  0)
 
 
die "Failed to create the FSEventStream" unless stream
 
FSEventStreamScheduleWithRunLoop(
  stream,
  CFRunLoopGetCurrent(),
  KCFRunLoopDefaultMode)
 
ok = FSEventStreamStart(stream)
die "Failed to start the FSEventStream" unless ok
 
begin
  CFRunLoopRun()
rescue Interrupt
  FSEventStreamStop(stream)
  FSEventStreamInvalidate(stream)
  FSEventStreamRelease(stream)
end