use Time::Piece qw(localtime);
use Time::Seconds qw(ONE_DAY);

my $t = localtime;
my $yesterday = $t - ONE_DAY();
my $tomorrow  = $t + ONE_DAY();
print "Today: ", $t->ymd(),"\n";
print "Yesterday: ", $yesterday->ymd(),"\n";
print "Tomorrow: ", $tomorrow->ymd(),"\n";