digFor

-- required ComputerCraft1.65
local block_names = {
  {"dirt",0}, "stone", {"wool",1}
}

function digFor(tbl)
  if not tbl then return turtle.dig() end

  local status, value = turtle.inspect()
  if status then
    local name = value["name"]
    local meta = value["metadata"]

    for i,v in ipairs(block_names) do
      if type(v)=="table" then
        if string.match(name,v[1]) and meta == v[2] then
          return turtle.dig()
        end
      else
        if string.match(name,v) then
          return turtle.dig()
        end
      end
    end
    return false, "No block to match"

  else
    return turtle.dig()
  end
end

while true do
  print(digFor(block_names))
  os.sleep(5)
end