If the site visitor requests a non-existent page, autosearch pluging will kick in to show the following:

1. Redirect to the index sub-page if one exists. For example, if :folder:index page exists but :folder page does not exist, and a visitor requests the :folder page, he/she will be automatically redirected to :folder:index page. The names of index subpages can be specified in the configuration manager.
2. If no index subpage is available, show the list of subpages (requires indexmenu plugin) and also the results of searching the requested page title. The search results is useful especially when you move your pages around and static links from outside world into your site become obsolete.

Information and download:

• Details and Download
  
• Alternate Details and Download (if the link above does not work).

zip file is not ok at all:

• Create folder autosearch, open zipfile with an unzipper, select the files in the folder and unzip only these to your created folder.
• In Linux, first create the autosearch directory (“mkdir autosearch”) in the same directory of zip file, then unzip it with “unzip autosearch.zip”. When it ask to overwrite the autosearch directory, say “n”. — Samuele Tognini 2008/08/27 17:46

You need to apply this patch to get latest indexmenu releases work:

diff -urN /tmp/autosearch/action.php ./autosearch/action.php
--- /tmp/autosearch/action.php  2007-07-03 12:15:00.000000000 +0200
+++ ./autosearch/action.php     2008-08-27 18:40:35.000000000 +0200
@@ -41,7 +41,7 @@
             die();
         }
       }
-      if($this->getConf('pagelist') && is_dir(dirname(wikiFN("$ID:dummy"))) &&
$indexmenu =& plugin_load('syntax', 'indexmenu')){
+      if($this->getConf('pagelist') && is_dir(dirname(wikiFN("$ID:dummy"))) &&
$indexmenu =& plugin_load('syntax', 'indexmenu_indexmenu')){
         $handled = $indexmenu->handle("{{indexmenu>$ID#2|js#default}}",null,nul
l,$this);
         $dummy_renderer = (object) array('doc'=>'');
         $indexmenu->render('xhtml',$dummy_renderer, $handled);

I made a few alterations to correctly handle start pages named as configured (start by default) instead of hard-coded index:

diff -ur autosearch.old/action.php autosearch/action.php
--- autosearch.old/action.php   2014-03-31 16:54:00.662421400 +0100
+++ autosearch/action.php       2014-03-31 16:53:11.133588500 +0100
@@ -23,6 +23,7 @@
                            array());
   }
   function handle_act(&$e, $param){
+    global $conf;
     global $ID;
     if($e->data != 'show' || strpos($ID,'talk:')===0) return;
 
@@ -36,6 +37,9 @@
       foreach($index_pages as $index){
         if($index == '@subpage_with_same_name')
           $index = noNS($ID);
+        if($index == '@start_page')
+          $index = $conf['start'];
+
         if(is_file(wikiFN("$ID:$index"))){
             header("Location: ".wl("$ID:$index", $perm < AUTH_CREATE ? "" : "auto_search_indexed=1"));
             die();
diff -ur autosearch.old/conf/default.php autosearch/conf/default.php
--- autosearch.old/conf/default.php     2009-05-20 17:50:38.000000000 +0100
+++ autosearch/conf/default.php 2014-03-30 23:40:27.858605200 +0100
@@ -1,4 +1,4 @@
 <?php
-$conf['index_pages'] = 'index,home,@subpage_with_same_name';
+$conf['index_pages'] = '@start_page,@subpage_with_same_name';
 $conf['pagelist'] = 1;
 $conf['search'] = 1;
diff -ur autosearch.old/conf/metadata.php autosearch/conf/metadata.php
--- autosearch.old/conf/metadata.php    2009-05-20 17:50:38.000000000 +0100
+++ autosearch/conf/metadata.php        2014-03-30 23:40:27.862105700 +0100
@@ -1,5 +1,5 @@
 <?php
 $meta['index_pages'] = array('multicheckbox',
-                          '_choices' => array('index','home','@subpage_with_same_name'));
+                          '_choices' => array('@start_page','@subpage_with_same_name'));
 $meta['pagelist'] = array('onoff');
 $meta['search'] = array('onoff');

Fernando Ribeiro