Minecraft Empty Chests Command Block

Solution 1:

As of the latest, latest snapshot (14w02b), this is most certainly possible. In fact, there's an easier way to do the whole thing now, which is awesome. With the /blockdata command added in the snapshot, you can modify and overwrite the contents of a tile entity (including a chest), and much, much more. The applications of /blockdata go beyond what I can fully comprehend at this point in time, but, for this specific case, it's not too hard.

Let's say for example your equipment chest is supposed to contain a notch apple, a gold sword, a bow, and a stack of arrows. The command for that would be /blockdata X Y Z {Items:[{id:322,Damage:1,Count:1,Slot:0},{id:283,Count:1,Slot:1},{id:261,Count:1,Slot:2},{id:262,Count:64,Slot:3}]}, replacing X Y and Z as appropriate. There's a lot of stuff going on in that command, but essentially, you are changing the data of the chest to contain the specified items. It's the same concept as using /setblock to spawn a new chest with these items, except instead of replacing the chest, you're overwriting its data.

In this more specific case, you want /blockdata 264 4 997 {Items:[{id:274,Count:1,Slot:0},{id:275,Count:1,Slot:1}]}.

And, of course, if you want an empty chest, all you need to do is use /blockdata X Y Z {Items:[]}

Solution 2:

You could have two chests set up and connected with a hopper from one to the other. Use the blockdata tag on the top chest to add the item. It will be sucked into the second chest, and added to whatever items are already there.