PHP Script Version Checking/Notification

Question

How can I check the version of my script against an online file to see if it's the latest version?

For clarification, I'm talking about a script I wrote, not the version of PHP. I'd like to incorporate a way for the end user to tell when I've updated the script.

Answer 1

To specify the second (more simple) solution phjr proposed:

Have a file version.txt on your own public server and include the following function into your deployed project/script:

define('REMOTE_VERSION', 'http://your.public.server/version.txt');

// this is the version of the deployed script
define('VERSION', '1.0.1');

function isUpToDate()
{
    $remoteVersion=trim(file_get_contents(REMOTE_VERSION));
    return version_compare(VERSION, $remoteVersion, 'ge');
}

version.txt should just contain the most recent version number, e.g.:

1.0.2

Answer 2

Per comments on this answer

// Substitue path to script with the version information in place of __FILE__ if necessary
$script = file_get_contents(__FILE__);
$version = SOME_SENSIBLE_DEFAULT_IN_CASE_OF_FAILURE;
if(preg_match('/<!-- Script version (\d*(\.\d+)*) -->/', $script, $version_match)) {
    $version = $version_match[1];
}

Answer 3

define('REMOTE_VERSION', 'http://your.public.server/version.txt');
define('VERSION', '1.0.1');
$script = file_get_contents(REMOTE_VERSION);
$version = VERSION;
if($version == $script) {
    echo "<div class=success> 
<p>You have the latest version!</p> 
</div>";
} else {
    echo "<div class=error> 
<p>There is a update available!</p> 
</div>";
}