How do you make a command block open a door on minecraft?

Answer 1

you cannot directly open a door with a command,but there are ways to open doors with command blocks:like have a command block next to a comparater (in the snapshot at mojang.com) and have the command block reapatadly get powerd by a clock and in the command block have:/testfor @a/p/f/r[selectors] and wire the comparator to the door and when someone meets the testfor selector the door opens!