Question: Does PHP have global variables that can be modified by one running script and read by another?

Answer: 
You can use [$\_SESSION](http://php.net/manual/en/book.session.php), i.e.:

**script1.php**

```
<?php
session_start();
$_SESSION['myVar'] = "something";
?>

```

**script2.php**

```
<?php
session_start();
echo $_SESSION['myVar'];
//something
?>

```
Each request is handled by a php instance of its own. Global variables in php are only accessible from within the same php instance. However you can use something like the [memchached module](http://docs.php.net/memcached) to share data between different instances (which should usually be faster than writing the data to the filesystem).