note about will_render and preview

[ikiwiki.git] / doc / plugins / write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 9c3a36b8fb516a72e0b3dbc01ad343348bd4173f..e1e057c007888fd44b5a41a1cd1c31f4b8a64cde 100644 (file)
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -222,8 +222,11 @@ source files that were rendered.
 
 Use this to hook into ikiwiki's cgi script. Each registered cgi hook is
 called in turn, and passed a CGI object. The hook should examine the
-parameters, and if it will handle this CGI request, output a page (including the http headers) and
-terminate the program.
+parameters, and if it will handle this CGI request, output a page
+(including the http headers) and terminate the program.
+
+Note that cgi hooks are called as early as possible, before any ikiwiki
+state is loaded, and with no session information.
 
 ### auth
 
@@ -478,8 +481,13 @@ If the destination directory doesn't exist, it will first be created.
 
 Given a page name and a destination file name (not including the base
 destination directory), register that the page will result in that file
-being rendered. It's important to call this before writing to any file in
-the destination directory.
+being rendered. 
+
+It's important to call this before writing to any file in the destination
+directory, and it's important to call it consistently every time, even if
+the file isn't really written this time -- unless you delete any old
+version of the file. In particular, in preview mode, this should still be
+called even if the file isn't going to be written to during the preview.
 
 Ikiwiki uses this information to automatically clean up rendered files when
 the page that rendered them goes away or is changes to no longer render