So I am making a 'magic trail', which is essentially wherever you walk and jump, a block will be placed below you. Unfortunately, the trail will always stick around and never go away. After a while this means that there will be a giant trail of blocks through the sky that looks pretty ugly. What I want to do is make a block disappear after a certain period of time, say, 7 seconds. Here are the commands and the setup for this project:

Command block #1: /setblock ~ ~ ~-1 redstone_block 0 destroy
Command block #2: /execute @a ~ ~ ~ /fill ~ ~-1 ~ ~ ~-1 ~ wool 0 replace  air
Redstone block: []

Setup:   #1 []

Note: Please don't try a method using a FallingSandEntity and Age because I want to have the player be able to actually walk on the blocks. If you use a FallingSandEntity the player will fall right through the block. Anyways, all help is appreciated, thanks! Also, if you want to try doing this with the fill command, I would want a 7x7x7 hollow cube surrounding the player so that the trail can't go outside the blocks. I just don't know how to do this.

  • 1
    Does the command to place a block output a signal? if so: run that redstone signal through a seven second long redstone circuit and then into a second command block. You'll still need to get the coordinates over to the second block somehow though. Since the player will have moved on...
    – Arperum
    May 21, 2014 at 14:26
  • Well, progress. I've made it so it won't fill any block with wool, just air. May 22, 2014 at 12:09
  • 1
    I would set a bunch of command blocks to remove wool blocks at every space around ~ ~-1 ~, except the actual block. That way, as the player moves away, the previous wool block enters this zone of 20 blocks (9 above, 9 below, 8 around) and is destroyed.
    – fredley
    May 22, 2014 at 12:13

2 Answers 2


I did something very similar to this, using a fill clock, scoreboard commands, and wither skulls.

Two scoreboard objectives were added, walkonair and lifetime. The first objective controls the ability to walk on air, and the second objective controls the "lifetime" of the blocks below the player.

The setup: Mechanic for walking on air.

  • What are in the two command blocks with pressure plates? May 22, 2014 at 22:38
  • By the way, great answer! I like your method of getting rid of the blocks instead of my method where it uses fill replace commands to make a hollow cube around the player. May 22, 2014 at 22:39
  • The command on the right is scoreboard players reset * and the one on the left is scoreboard players set @a[r=1] walkonair 1. (They work as a toggle for the ability to walk on air.)
    – ghipkins
    May 23, 2014 at 22:48
  • Sorry to pester, but how do I set up a fill clock with the two command blocks? I only know how to do the /setblock one. May 23, 2014 at 23:19
  • One block does /fill ~ ~1 ~ ~ ~1 ~ redstone_block and the other command block (two blocks above the first) does /fill ~ ~-1 ~ ~ ~-1 ~ stone. You'll probably have to adjust the orientation for the clock to actually start.
    – ghipkins
    May 31, 2014 at 22:54

This will only work the PC edition, but you can place a command block with some sort of repeating signal. In 1.9+ just set the command to always active and repeat, and on 1.8- you can either take 2 hoppers into each other with a comparitor, or repeaters running into each other with 2 ticks delay.

However, the best thing to do, and what you may be already using, would be to have two command blocks constantly filling in an area with redstone blocks and stone to update the command blocks every tick.

So in the 1st command block put

/execute ~ ~ ~ detect ~ ~-1 ~ minecraft:air setblock ~ ~-1 ~ minecraft:[block to place]

Then in the next four command blocks put these commands to remove all of the blocks that where placed around the player

/execute ~ ~ ~ detect ~1 ~-1 ~ minecraft:[block to place] setblock ~1 ~-1 ~ minecraft:air

/execute ~ ~ ~ detect ~ ~-1 ~ minecraft:[block to place] setblock ~-1 ~-1 ~ minecraft:air

/execute ~ ~ ~ detect ~ ~-1 ~1 minecraft:[block to place] setblock ~ ~-1 ~1 minecraft:air

/execute ~ ~ ~ detect ~ ~-1 ~-1 minecraft:[block to place] setblock ~ ~-1 ~-1 minecraft:air

These may seem similar, but each one tests for and removes a different block around the player. For even greater success, create four more that remove the corner blocks around the player. This technique is good, as it only removes the blocks that have been previously placed.


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