Execute Commands

How the game reads a chain

/execute is read from left to right. Most subcommands change who runs the rest of the chain, where, or whether it runs at all, and the chain has to end with run plus a command, or with a condition. Order matters more than anything else here.

execute as @e at @s run tp ^ ^ ^1 moves every entity one block forward. Swap the first two parts to execute at @s as @e run tp ^ ^ ^1 and all of them land one block in front of you instead.

When as or at picks several entities, the chain forks and everything after that point runs once for each of them. A condition that fails only ends its own branch.

The four kinds of subcommand

Modifiers

align, anchored, as, at, facing, in, on, positioned, rotated and summon set the executor, position, rotation, dimension and anchor. on and summon were added in Java 1.19.4.

Conditions

if or unless, followed by biome, block, blocks, data, dimension, entity, function, items, loaded, predicate or score. At the very end of a chain a condition just reports whether it passed. The newer tests are biome (1.19.3), dimension and loaded (1.19.4), function (1.20.2) and items (1.20.5).

store

store result saves the return value and store success saves 1 or 0, into a block, a bossbar, an entity, a score or a storage. After a fork each branch stores its own value, and a later branch overwrites an earlier one at the same spot.

run

The command to carry out. It can appear once, at the end.

A pattern worth copying

execute as @a at @s if block ~ ~-1 ~ minecraft:magma_block run effect give @s minecraft:fire_resistance 5

This gives five seconds of fire resistance to every player standing on magma. as picks each player, at moves to where they stand, the condition checks the block under their feet and run only fires for the players who pass. Put it in a tick function and the effect never wears off while they stay on the block. Functions and schedules are with the logic commands. /execute needs permission level 2.