In my initial response I answered your question about using system; however, it occurs to me that you probably want to capture that output and do something with it. So, if you replace

system("ls -1 $datum");
[download]

with

my @matches = `ls -1 $datum`;
[download]

you'll now have an array of matches that you can process further. If that processing was

print for @matches;
[download]

you'll get identical output to what I originally posted.