Finding a file with a specific name with any extension

You need glob().

$compartment = "2";

$files = glob("/path/to/files/$compartment.*"); // Will find 2.txt, 2.php, 2.gif

// Process through each file in the list
// and output its extension
if (count($files) > 0)
foreach ($files as $file)
 {
    $info = pathinfo($file);
    echo "File found: extension ".$info["extension"]."<br>";
 }
 else
  echo "No file name exists called $compartment. Regardless of extension."

by the way, what you are doing above is crying for a loop. Don' repeat your code blocks, but wrap one of them into this:

 $compartments = array(1, 3, 6, 9); // or whichever compartments 
                                    // you wish to run through

 foreach ($compartments as $compartment)
  {
   ..... insert code here .......
  }

Look up:

• glob — Find pathnames matching a pattern
• fnmatch — Match filename against a pattern
• pathinfo — Returns information about a file path