If this is meant to be run only in a mod_perl environment, your best bet is probably to make Drall into a module, with a handler which looks something like:

use Apache::Constants qw(:common DIR_MAGIC_TYPE);
sub handler {
  $r = shift;
  return DECLINED unless $r->content_type eq DIR_MAGIC_TYPE;
  do_stuff();
}
[download]

Documentation on the stages of an Apache request, and hence the uses of the mod_perl hooks into them, can be found in the excellent mod_perl book, which has some chapters available online. Chapter 7 may help with what you are trying to do.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'

I did something like this using a simple CGI script, which employs caching via File::Cache.

You can see it at http://crazyinsomniac.perlmonk.org/perl/index/

All you need to do is add DirectoryIndes ... whatever you got ... /cgi-bin/scripto.pl, and have that script do pretty much what mine does (get a list of files and dirs in the current directory).

____________________________________________________
** The Third rule of perl club is a statement of fact: pod is sexy.

If I understood correctly, you want Drall to be called with the current location whenever a file index.html isn't found. You can do as follow.

Replace the redirect to Drall with a call to a printenv script:

DirectoryIndex index.html /cgi-bin/printenv.pl

This way, whenever you visit a location without index.html, you get redirected to the script. If now you look at what printenv.pl says, you will see many headers prefixed by REDIRECT_, and the uri you were looking for is in REDIRECT_REQUEST_URI.

So, the solution is to substitute printenv.pl with a script which issues a redirect to Drall with the correct paramaters, something like

use CGI;
$redir = '/cgi-bin/drall.pl?left='. $ENV{REDIRECT_REQUEST_URI};
print CGI::redirect(-uri => $redir);
[download]

Hope this helps! Ciao, Valerio

(I am original poster, damn cookies screwed up)
that is EXACTLY what I needed, and thanks for explaining it; there was no REDIRECT_REQUEST_URI, but there is a REDIRECT_URL as well as a REQUEST_URI, both seem to be the same, so I am happy using REDIRECT_URL.
(perl 5.6.1, apache 1.3.26, solaris 2.6, no mod_perl(?))

Thanks again,
-k

You are welcome :) Assuming you are working under some kind of unix, you can use this command to discover what kind of HTTP server is used:

lynx -mime_header http://www.perl.com | grep -E "^Server: "

Ciao, Valerio