This is just a little something I wrote up in about 20 minutes. The place where I work at has a few virtual servers, and most users have CGI scripts on them. Problem is, they have the .cgi extension on them and I couldn't take advantage of the speed of mod_perl, so I wrote a PerlHandler to automatically determine if a CGI script was written in Perl or some other language and point it to the correct handler.
CGIAutoDetect.pm (this should go in /usr/local/apache or wherever you install your PerlHandlers): 
#!/usr/bin/perl

# CGIAutoDetect: take full advantage of mod_perl without renaming scri
+pts
# Mooneer Salem <mooneer@translator.cx>

package CGIAutoDetect;

use Apache::Constants qw(:common);
use Apache::PerlRun;
use CGI::Carp qw(fatalsToBrowser);

sub handler {
        my $r = shift;
        my $filename = $r->filename;
        my $line;

        open(FP, $filename) or sub {
                        $r->content_type("text/html");
                        $r->print("$filename: not found");
                        return OK;
                };

        $line = <FP>;
        close(FP);

        if ($line =~ /perl/o) {
                $r->push_handlers("PerlHandler", \&Apache::PerlRun::ha
+ndler);
                $r->handler('perl-script');
        } else {
                $r->handler('cgi-script');
        }

        return DECLINED;
}

[download]
You also need something like this in your httpd.conf file (make sure you comment out the AddHandler cgi-script line before you add it though): 
PerlModule CGIAutoDetect
    
<Files *.cgi>
SetHandler perl-script   
PerlHandler CGIAutoDetect
PerlSendHeader On
Options ExecCGI
</Files>

[download]

In reply to Automatically using mod_perl by Anonymous Monk

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