my $SECS_IN_A_DAY = 86400;  # 60 secs * 60 mins * 24 hrs

my ($day, $month, $year) = (localtime(time-$SECS_IN_A_DAY))[3..5];
$month++;
$year += 1900;

# $month = "0".$month if (length($month) == 1); # for dd-mm-yyyy.txt files.
# $day = "0".$day if (length($day) == 1); # for dd-mm-yyyy.txt files.

print "File is $day-$month-$year.txt\n";