One thing I did (it was mostly to improve my advanced data structure understanding) was make the config file a perl module.

package conf;

%enable = (
    #qmail
    'alias' =>
        {
            'directory'    =>    $qmaildir,
            'command'      =>    "putdiff.sh /var/qmail/alias alias"
        },
    'aliases' =>    
        {
            'directory'    =>    $qmc ,
            'command'      => "newaliases"
        },
    ::snip::
};
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Then, in the main program, I just require "/usr/local/etc/mymodule.pm"; and then I can refer to it as:

$conf::enable{'aliases'}->{'command'}

~~

naChoZ