my $yesterday = get_date (-1);

print "Yesterday = $yesterday\n";

sub get_date {
  my $offset = shift || 0;
  my $ts = time + $offset*60*60*24;
  my ($day,$month,$year) = (localtime($ts))[3,4,5];
  sprintf ("%02s%02s%04s",$day,$month+1,$year+1900);
}

rename "d:/EOD/20 January 2002/system.csv", "d:/EOD/20 January 2002/?????_system.csv";
rename "d:/EOD/20 January 2002/sales.csv", "d:/EOD/20 January 2002/?????_sales.csv";

my $source = "d:/EOD/20 January 2002/?????_system.csv";
my $source1 = "d:/EOD/20 January 2002/?????_sales.csv";
my $destination = "c:/New EOD/?????_system.csv";
my $destination1 = "c:/New EOD/?????_sales.csv";

open IN, $source or die "Can't read source file $source: $!\n";         
open IN, $source1 or die "Can't read source file $source1: $!\n";          
open OUT,">$destination" or die "Can't write on file $destination: $!\n";  
open OUT,">$destination1" or die "Can't write on file $destination1: $!\n";

print 'Renamed csv files with date and copied to new directory';

while (<IN>) {
	print OUT $_;
}