On a more general note, it is my preference that any time a function (or method) accepts more than one parameter then it is time to use "named parameters" to prevent future headaches.

For example:

#!/usr/bin/perl -w

use warnings;
use strict;

sub processDir {
    my $args = shift; # note, default for shift here is @_;

    my $ret = qx($args->{script} $args->{dir});
    chomp($ret);
    print qq(Output:"$ret"\n) if $args->{verbose};
}

# Normally via environment variable
my $script = "echo -e"; 
# Normally via glob and processing in this script
my @dirs = qw(dir1 dir2 dir3);
# Normally via Getopt::Long
my $verbose = 1;

for my $dir (@dirs) {
    # Do some stuff, then:
    processDir( { dir => $dir, script => $script, verbose => $verbose 
+} );

    # which would be exactly the same as:
    processDir( { script = > $script, dir => $dir, verbose => $verbose
+ } );

    # or this:
    processDir( { verbose => $verbose, script => $script, dir => $dir 
+} );

    # or any other combination you can think of.
}
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There is much, much more that can be said about this, but knowing about the idea should give you the start for some very interesting research.

Note: Yes, I know I have left out a LOT of potential gotchas in this very crude example. But I feel the essence is clear and a minimal amount of research should reveal a wealth of information on the concept that will stand OP in good stead for a long time to come.

Update: Another advantage of named parameters is that with a little thought you can deal with the situation where you might start out with a single parameter passed in the normal way, but then allow for named parameters in the future. This example is taken from (my module) DateTimeX::Fiscal::Fiscal5253 (Please read the docs on CPAN to understand just exactly what this allows):

sub contains
{
    my $self = shift;
    my %args = @_ == 1 ? ( date => shift ) : @_;

    $args{date} ||= 'today';
    $args{style} ||= $self->{_style};

    croak 'Unknown parameter present' if scalar(keys(%args)) > 2;

    ...
}
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You will find several examples of how I use this technique in the source.