Unless the examples are shown as executed in the ISQL tool, this can be made also in the Virtuoso/PL code.

SQL> select php_str ('<?php echo "Hello World"?>');
callret
VARCHAR
_______________________________________________________________________________

Hello World

SQL> select php_str ('<?php print abs (-1);?>');
callret
VARCHAR
_______________________________________________________________________________

1

SQL> set MACRO_SUBSTITUTION off;
SQL> select php_str ('<?php echo $a?>', 'a=Hello+World');
callret
VARCHAR
_______________________________________________________________________________

Hello World

SQL> select php_str ('<?php echo $a?>', vector ('a', 'Hello World'));
callret
VARCHAR
_______________________________________________________________________________

Hello World

SQL> select php_str ('<?php echo "$a $b"?>', 'a=Hello+World&b=Hello+Again+World');
callret
VARCHAR
_______________________________________________________________________________

Hello World Hello Again World

SQL> select php_str ('<?php $a=1; $b=2; $c=3; $d=$a+$b+$c; echo $d?>');
callret
VARCHAR
_______________________________________________________________________________

6

SQL>  select php_str ('<?php $a=8; $b=4; $c=8; echo $a|$b&$c?>');
callret
VARCHAR
_______________________________________________________________________________

8

This is test how the PHP processor can instruct the HTTP server to send a custom response and header to the user agent. The following page can stored on the file system or in the WebDAV repository (in which case execution rights must be enabled). Hitting that page will redirect user-agent to the index.html page in HTTP server root.

<?php
  header ("HTTP/1.1 302 Found");
  header ("Location: /index.html");
?>