%fdat = (
    'redirect_sam' => 'boondoggle'
);

$fdat{$_} = $fdat{"redirect_$_"} 
    for map /^redirect_(.*)$/, keys %fdat;

##</code><code>##

for(keys %fdat) {
    $fdat{$1} = $fdat{$_} if /^redirect_(.*)$/;
}