Watches local directory (and subdirectories) and does rsync to remote server when a file is added, modified, or deleted.

watcher.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'rb-fsevent'

def sync(local, host, remote)

    timehack = Time.now;
    print "syncing... #{timehack}\n";

    # Construct the bash command that runs rsync.
    cmd = "rsync " +

        '-e "/usr/bin/ssh -i PATH_TO_KEYFILE" ' +

        "--recursive " +  # Sync all subdirectories.
        "--copy-links " + # Include symlinked
        "--compress " +   # Compress before transferring (faster)
        #  "--progress " +   # Show progress during transfer (quite verbose)

        # Exclude stuff that you don't want to transfer.
        "--exclude '.git' " +
        "--exclude '.svn' " +
        "--exclude '.hg' " +
        "--exclude '.idea' " +      # PHPStorm
        "--exclude '.DS_Store' " +  # Mac only

        "--delete " + # If you delete files locally, then also delete remotely.

    local + " " + host + ":" + remote

  # Run the command.
  system cmd

end

local  = 'PATH_TO_LOCAL_FILES'
host   = 'USERNAME@TARGET_SERVER_DOMAIN'
remote = 'PATH_ON_TARGET_SERVER'

# FSevents wont detect changes in subdirectories that are symlinks
# (because technically the symlink has not changed)
# so list all symliks an monitor them separately
paths = []

# Horribly unreadable command to recursively find all symlink paths in a directory:
symlinks_cmd = "find "+ local + " -type l -exec ls -l {} \\; | grep -no '\\->.*$' | cut -c 6-"
f = open("|" + symlinks_cmd)
output = f.read()
output.each_line { |path| paths.push path.sub(/\n/, '') }

# Finally, add the root directory.
paths.push local

fsevent = FSEvent.new
fsevent.watch paths do
    sync(local, host, remote)
  end
fsevent.run