ls files.* | script.pl
OR
./script.pl files.ext files.ext2 files.ext3

##</code><code>##

./script.pl -d /my/dir/for/files -f files

##</code><code>##

 ....
 $defaultdir = "/usual/place/to/look";
 $dir = $opt_d;
 $dir = $defdir unless -e $dir;
 $defprefix = "files\.";
 $prefix = $opt_f;
 $prefix = $defprefix unless $prefix;
 opendir(LS, $dir) || die "couldn't open dir\n";
 while(my $file = readdir(DIR)) {
	if($file =~ /^$prefix/) {
		push @FILES,$file;
	}
 }
 ....