I have a similar question. I have tried my $filesize = 0; and  my $filesize = -s $$file; and I am getting the same warning only when the file size is 0. I have searched but I have not found anything useful. Use of uninitialized value $filesize in numeric ne (!=) Can you please help? 
$output_file = 'output_file';

backup_the_data(\$output_file);

sub backup_the_data {
   my ($file) = @_;

   my $filesize = 0;
   # my $filesize = -s $$file;
   $filesize = -s $$file;

   if ($filesize != 0){ 
      copy($$file, $$file . '_backup');
   }
}

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In reply to Re^2: Use of uninitialized value by kevyt
in thread Use of uninitialized value by Win

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