The DIR handle is GLOBAL. Therefore the recursive call clobbers (overwrites) the "parent"'s dirhandle so when the call returns the dirhandle is at the end of the list and therefore cannot return anything.

You have to add 

local *DIR;

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into the subroutine, above the opendir or use a lexical dirhandle: 
sub lc_filenames{
    my($dir)=@_;
    $dir||="."; 
    opendir my $DIR, $dir;
    while(defined(my $file=readdir $DIR)){
...

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This syntax will not work in older Perls! You may need to add use FileHandle; and declare the $DIR above the opendir like this: 
my $DIR;
opendir $DIR, $dir;

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Another nit. You do not close the dirhandle! You should!

Jenda
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.
   -- Rick Osborne

Edit by castaway: Closed small tag in signature

In reply to Re: problems returning from recursive subroutine by Jenda
in thread problems returning from recursive subroutine by melguin

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