turn this into a tip

doc/tips.mdwn

@@ -1,5 +1,7 @@
 This page is a place to document tips and techniques for using ikiwiki.
 
+[[toc ]]
+
 ## wikiannounce
 
 One thing I use ikiwiki for is the web pages for software projects I
@@ -33,3 +35,8 @@ access. --[[JoshTriplett]]
 [[This_article|issue_tracking]] has some thoughts and tips on using ikiwiki
 as a BTS, as is done on this very wiki to track [[bugs]] and [[todo]] items
 for ikiwiki.
+
+## redirections for usedirs
+
+Want to turn on the `usedirs` setting on an existing wiki without breaking
+all the links into it? Here's [[how|usedirs_redirections]].

doc/tips/usedirs_redirections.mdwn

@@ -0,0 +1,22 @@
+Want to turn on the `usedirs` setting on an existing wiki without breaking
+all the links into it? Here's a way to do it for Apache, using the
+RewriteEngine. This example is for a wiki at the top of a web site, but can
+be adapted to other situations.
+
+	# pages
+	RewriteCond $1 !^/~		# these pages
+	RewriteCond $1 !^/doc/		# are not part of
+	RewriteCond $1 !^/ajaxterm	# the wiki, so
+	RewriteCond $1 !^/cgi-bin/	# don't rewrite them
+	RewriteCond $1 !.*/index$
+	RewriteRule (.+).html $1/ [R]
+	
+	# rss feeds
+	RewriteCond $1 !^/~
+	RewriteCond $1 !.*/index$
+	RewriteRule (.+).rss $1/index.rss
+	
+	# atom feeds
+	RewriteCond $1 !^/~
+	RewriteCond $1 !.*/index$
+	RewriteRule (.+).atom $1/index.atom

doc/todo/Document_redirections_for_use_with_usedirs.mdwn

@@ -1,29 +0,0 @@
-Now that ikiwiki supports using page/index.html rather than page.html, how about some mechanism to automatically generate a .htaccess file with "Redirect permanent" lines for each such page?
-
-> I was thinking of using an apache RewriteRule for this, haven't written
-> one yet though. --[[Joey]]
-
-> Here's a RewriteRule that I'm using for <http://kitenet.net/>, which
-> has an wiki at the top level that's using index.htmls, and some
-> other stuff that shouldn't be rewritten.
-
-	RewriteCond $1 !^/~
-	RewriteCond $1 !^/doc/
-	RewriteCond $1 !^/ajaxterm
-	RewriteCond $1 !^/cgi-bin/
-	RewriteCond $1 !.*/index$
-	RewriteRule (.+).html $1/ [R]
-	
-	RewriteCond $1 !^/~
-	RewriteCond $1 !.*/index$
-	RewriteRule (.+).rss $1/index.rss
-	
-	RewriteCond $1 !^/~
-	RewriteCond $1 !.*/index$
-	RewriteRule (.+).atom $1/index.atom
-
->> Nice solution.  I think this would work for a newly-converted wiki as well,
->> using a condition to limit rewrites to that wiki's directory, and the
->> rewrite rule you propose.  Thus, autogenerating seems unnecessary; we
->> should just have a documented, known-working RewriteCond and RewriteRule
->> for wikis that want to turn on the `usedirs` option.  --[[JoshTriplett]]