Script used to play a sound when a specific image is present in a page. It fetches the page every 5 minutes and checks for the image presence. If the image is found it starts playing the alarm in a loop.

gistfile1.groovy

#!/usr/bin/env groovy

@Grapes( @Grab('org.jsoup:jsoup:1.6.1'))

import org.jsoup.*
import org.jsoup.nodes.* 

// a wrapper closure around executing a string                                  
// can take either a string or a list of strings (for arguments with spaces)    
// prints all output, complains and halts on error                              
def runCommand = { strList ->
  assert ( strList instanceof String || ( strList instanceof List && strList.each{ it instanceof String }))
  
  def proc = strList.execute()
  proc.in.eachLine { line -> println line }
  proc.out.close()
  proc.waitFor()

  print "[INFO] ( "
  if(strList instanceof List) {
    strList.each { print "${it} " }
  } else {
    print strList
  }
  println " )"

  if (proc.exitValue()) {
    println "gave the following error: "
    println "[ERROR] ${proc.getErrorStream()}"
  }
  assert !proc.exitValue()
}

found = false
img2find = 'http://imageshack.us/a/img834/2894/topoamineirogeral.jpg'
while (!found) {	
  try {
      println 'fetching page...'
    	Document doc = Jsoup.connect("http://www.totalacesso.com/event/detail/421").get();
    	def results = doc.select("div.ContentEventDetail img")
    	println "looking for image: $img2find"
    	if(results.find { it.attr('src').equals(img2find)}) {
    		println "Image found!!"
    		found = true
    	} else {
    		println 'Not yet.. Sleeping...'
    		doc.sleep(300000)
    	    println 'Trying again...'
    	}
  } catch(Throwable t) {}
}

if (found)
	while(true)
		runCommand('paplay /usr/share/sounds/ubuntu/stereo/phone-incoming-call.ogg')