perl -MDate::Calc -E ' use Date::Calc qw(Add_Delta_Days);say join "-", Add_Delta_Days(2011,11,30,1);'
2011-12-1
В сценарии (не очень безопасно)
use Date::Calc qw(Add_Delta_Days);
my $entered_date = "2011-12-31";
print join "-", Add_Delta_Days(split(/-/,$entered_date),1);'
2012-1-1