use strict;
use warnings;

use File::Spec  qw( catfile );
use Time::Local qw( timegm );


sub localdate {
   my ($time) = @_;
   my ($y, $m, $d) = (localtime($time))[5, 4, 3];
   $y += 1900;
   $m += 1;
   return ($y, $m, $d);
}

sub previous_day {
   my ($y, $m, $d) = @_;
   # Use GMT since all days are 24*60*60 seconds long in GMT.
   my $prev = timegm(0, 0, 0, $d, $m-1, $y) - 24*60*60;
   my ($p_y, $p_m, $p_d) = (gmtime($prev))[5, 4, 3];
   $p_y += 1900;
   $p_m += 1;
   return ($p_y, $p_m, $p_d);
}

sub today     { return localdate(time());     }
sub yesterday { return previous_day(today()); }


{
   my ($yd_y, $yd_m, $yd_d) = yesterday();

   my $dir = ...;

   opendir(my $dh, $dir)
      or die("Unable to open log dir \"$dir\": $!\n");

   while (my $file_name = readdir($dh)) {
      my $file_full = catfile($dir, $file_name);
      next if ! -f $file_full;

      my $mtime = (stat($file_full))[9];
      my ($f_y, $f_m, $f_d) = localdate($mtime);

      if (  $f_y == $yd_y
         && $f_m == $yd_m
         && $f_d == $yd_d
      ) {
         ...copy the file...
      }
   }
}