Sindbad~EG File Manager

<?php
$OutputDir = "otter/projects/";
$InputDir  = "otter/projects/";
$ExampleDir  = "examples/";
$OtterDir  = "otter"; // Otter or Otter-lambda executable file location.
$ExecuteLocation = "$OtterDir\\otter2.exe"; // or Otter-lambda
$inputfile  = "";
$outputfile = "";

function GenerateFileName()
{	// Each time this function is called it generates a unique new name.
	$name = "otter-".time();
	return $name;
}

function RunOtterByText($text)
{
	global $InputDir, $OutputDir, $inputfile, $outputfile;
	$Filename = GenerateFileName();
	$inputfile  = $InputDir.$Filename.".in";
	$outputfile = $OutputDir.$Filename.".out";
	file_write($inputfile,$text);  // $OtterInput comes from the HTML form.
	return RunOtterByFile($inputfile,$outputfile);
}

function RunOtterByFile($infile,$outfile)
{
	global $ExecuteLocation;
	$Execute = $ExecuteLocation." <".$infile." >".$outfile;
	exec($Execute);
	return file_read($outfile);
}

function file_write($filename, $data) 
{    echo("Trying to open $filename");
	$fh = fopen($filename, "wt"); 
	if ( !$fh ) {
		echo "ERROR: Could not open the file for writing.<BR>";
		exit();
	}
	$bytes_written = fwrite($fh, $data);
	fclose($fh);
	$bytes_written; 
}

function file_read($filename, $use_include_path = 0)
{
	$successful = 0;
	$file = fopen($filename, "rt", $use_include_path);
	if ($file) {
		while ( !feof($file) ) {
			$line = fgets($file,4096);
			if ( strstr($line,"PROOF") )
				echo "<B><font color=#0000ff>";
			echo "$line<br>";
			if ( strstr($line,"end of proof") )
				echo "</B></font>";
		}
		$successful = 1;
		fclose($file);
	} else {
		echo "ERROR: Could not open the file for reading.<BR>";
		exit();
	}
	return $successful;
}

function print_last($inputf,$outputf)
{
	echo "<HR><table width=\"700\" border=\"0\" align=\"center\">
	  <tr>
	    <td><a href=\"$inputf\">Download The Input File</a></td>
	    <td><a href=\"$outputf\">Download The Output File</a></td>
	  </tr>
	</table><BR>";
}

?>