Melee turtle program

I'm looking for a program for a melee turtle to make it attack for a limited time(for about 3 seconds)
and not forever.

Split into new topic.

The simple way:

for i=1,<somenumber> do
  turtle.attack()
  sleep(0.5)
end

The higher the number you put in place of "<somenumber>", the more times the loop will repeat and hence the longer the turtle will attack.