From: Robert Klemme <shortcutter@...>
Date: 2006-10-27T04:25:16+09:00
Subject: Re: Ruby fs watcher?

Paul Lutus wrote:
> This problem is easily solved, and in a portable way. You create a list of
> the files and their modification times, then sleep for some interval, then
> wake up and compare the stored modification times with the new ones, also
> test for any new files. Take action on any new or modified files. Maybe 25
> lines of Ruby code.
> 
> Be sure to sleep for an interval between tests, otherwise your script will
> hog the processor.

You rather need the mtime of the directory and only that - at least if 
you are interested in /new/ files only:

require 'set'

last = nil
set = Set.new

loop do
   current = File.mtime "."
   if last.nil? || last < current
     s = Dir["*"].to_set
     p s - set
     set = s
     last = current
   end
   sleep 1
end


Test run:

$ !ru
ruby /cygdrive/c/Temp/watch.rb &
[1] 1432

robert@fussel ~
$ #<Set: {"xx", "x", "bin", "a.1234"}>
touch foo

robert@fussel ~
$ #<Set: {"foo"}>
touch bar

robert@fussel ~
$ #<Set: {"bar"}>
touch bar

robert@fussel ~
$ touch baz

robert@fussel ~
$ #<Set: {"baz"}>

Kind regards

	robert