I have to recommend looking at some date modules on cpan but there are a lot to choose from so if that is all you need to do, and all you'll ever need to do you could use something like this:

#!/usr/bin/perl -w
use strict;

my $time = time;
my $date = date_format($time);
print "Now: $date\n";

my $tendays = date_format( $time + ( 10 * 24 * 60 * 60 ) );
print "10 days from now: $tendays\n";

my $thirtydays = date_format( $time + ( 30 * 24 * 60 * 60 ) );
print "30 days from now: $thirtydays\n";

sub date_format{
  my $seconds = shift;
  my @bits = localtime($seconds);
  $bits[4]++;
  $bits[5] += 1900;
  return sprintf "%02.0f-%02.0f-%04.0f %02.0f:%02.0f:%02.0f", ($bits[3
+],$bits[4],$bits[5],$bits[2],$bits[1],$bits[0]);
}
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my sprintf'n prolly isn't the best, but it seems to work..

cheers,

J