You can use a custom
sort block to do it. The block gets called for every sort iteration with the special variables
$a and
$b set to two of the items. In this case, they will be references to the various hashes in your array. You can then use the
cmp operator to compare the
file_name key alphabetically.
my @sorted = sort { $a->{file_name} cmp $b->{file_name} } @files;