.htaccess

<IfModule mod_rewrite.c>

  RewriteEngine on

  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]
</IfModule>

files-filtered.txt

./js/
./js/stopExecutionOnTimeout.js
./js/jquery.quovolver.js
./js/hello.html
./js/jquery.quovolver
./qss/
./qss/index.html
./rss/
./rss/sample.xml
./TOCs/
./TOCs/c10140.html

files.txt

./js/
./js/stopExecutionOnTimeout.js
./js/jquery.quovolver.js
./js/hello.html
./js/jquery.quovolver
./qss/
./qss/index.html
./rss/
./rss/sample.xml
./rss/BIO.xml
./rss/BIR.xml
./tex/
./tex/index.html
./tex/Manual.pdf
./wol/
./wol/html.php
./wol/lib.php
./wol/test.php
./wol/index.php
./wol/DEADJOE
./wol/wml.php
./wmicon.gif
./TOCs/
./TOCs/c3126.html
./TOCs/c5303.html
./TOCs/c9913.html
./TOCs/c4097.html
./TOCs/c6274.html
./TOCs/c8451.html
./TOCs/c7235.html
./TOCs/c1509.html
./TOCs/c6019.html
./TOCs/c4902.html
./TOCs/c537.html
./TOCs/c1263.html
./TOCs/c5873.html
./TOCs/c1008.html
./TOCs/c5618.html
./TOCs/c10140.html

render-matching-lines-as-links.php

<?php

enforce_httpauth_user_pass('SECRET_USERNAME', 'SECRET_PASSWORD');

$search_for = $_GET['q'];
$file = $_GET['filter'] == 1 ? 'files-filtered.txt' : 'files.txt';
$domain = $_GET['domain'] ? $_GET['domain'] : 'http://press.princeton.edu';


// optimized for blank queries
if(!$search_for) {
// the following line prevents the browser from parsing this as HTML, debug.
  header('Content-Type: text/plain');
  readfile($file);
}

$matches = get_matching_string($file, $search_for);
print_array_as_links($matches, $domain);

/**
 * Strips off leading "/" or "./".
 **/
function strip_leading_prefixes($line, $prefixes) {
  foreach($prefixes as $prefix) {
    if (strpos($line, $prefix) === 0) {
      $line = substr($line, strlen($prefix));
    }
  }
  return $line;
}

/**
 * Opens $file, returns an array of strings that start with $beginning.
 **/
function get_matching_string($file, $beginning) {
  $matches = array();
  $fh = fopen($file, 'r') or die($php_errormsg);
  while (!feof($fh)) {
    $line = fgets($fh);
    $line = trim($line);
    $line = strip_leading_prefixes($line, array("/", "./"));

    if (strpos($line, $beginning) === 0) {
      $matches[] = trim($line);
    }
  }
  fclose($fh);

  return $matches;
}

/**
 * Prints $matches wrapped in HTML <a> tags pointing to $domain.
 **/
function print_array_as_links($matches, $domain) {
  foreach($matches as $match) {
    print "<a href='$domain/$match'>$match</a><br />\n";
  }
}

function enforce_httpauth_user_pass($auth_user, $auth_password) {
  if (!isset($_SERVER['PHP_AUTH_USER'])
        || $_SERVER['PHP_AUTH_USER'] != $auth_user
        || $_SERVER['PHP_AUTH_PW'] != $auth_password
  ){
    header("WWW-Authenticate: Basic realm=\"Secure Realm\"");
    header("HTTP/1.0 401 Unauthorized");
    echo "Provide username + password please";
    exit;
  }
}