PHP - Email notification whenever a remote file changes - php

Question

I was wondering if there's a way to have a php script on my web server email me whenever a file from another web server changes.
For instance, there's this file that changes frequently: http://media1.clubpenguin.com/play/en/web_service/game_configs/paper_items.json
I blog about a game and that file is very important for creating post on updates before my competitors. I often forget to check it though.
Is there a way to have a script email me whenever that file updates, or check that file to see if it has updated, and email me if it has?

Answer 1

Use crontab to setup checking script to run once a minute and compare this file with your locally stored version (or use md5 checksums instead - it will differ if file changes).
file_get_contents('http://url-to-file', 'checkfile.tmp');
if (md5(file_get_contents('lastfile.tmp')) != md5(file_get_contents('checkfile.tmp')))
{
//copy checkfile to lastfile
unlink('lastfile.tmp');
copy('checkfile.tmp', 'lastfile.tmp');
//send email or do something you want ;)
}

Answer 2

You need have this two files in same folder.
old.json
scriptForCron.php
In scriptForCron.php write:
$url='http://media1.clubpenguin.com/play/en/web_service/game_configs/paper_items.json';
$ch = curl_init($url);
curl_setopt($ch,CURLOPT_CONNECTTIMEOUT, 5);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
$execute = curl_exec($ch);
$fp=fopen('old.json','w+');
$oldjson=fread($fp,filesize('old.json'));
if($execute!=$oldjson){
mail('your#mail.com','Yoohoo', 'File changed');
fputs($fp,$execute);
}
fclose($fp);
And then add scriptForCron.php to cron job.
You can ask hosting support for it.

Answer 3

This code does not check for updates in realtime - it would be pretty much impossible - but every 1 hour/minute.
First, save a file on your system which has the same contents as this. Name it any way, for example paper_items.json.
Now make a file named checkitems.php. Read the file which changes frequently, compare if it's contents are equal to your paper_items.json. If equal, nothing to do, if not, save the online file to your local paper_items.json and use PHP's mail() to email you something like "there was a change".
Finally, set up a cron job to run this every n (for example 1) hour or 1 minute, etc.