Below is the code which does the above.

No it doesn't.

You stripped too much or something is seriously broken in the code, e.g. the variable $dir is used but never assigned. Apart from that: Your process_file() function has 2 problems - the first one is that you open/close the logfile file handle for every file that is being processed. The other one is

sub process_file {
 ...
  if (-f $dummy) {
    ...
    open(my $fh, ...
    ...
  }
  close $fh;
}
[download]

'close()' is useless because by the time it is reached the variable $fh is no longer in scope. You're not a friend of strict and warnings, right?