my %template = (
    apachectl => 'my_apachectl',
    dname => 'my_foo',
);

open my $fh, '<', $apachectl_template
    or die "Failed to open '$apachectl_template': $!";
my $template = do { local $/; <$fh> };
$template =~ s/\$(\w+)/$template{$1} || $1/ge;