Minecraft/Commands

Commands can be executed on any version of Minecraft which has the chat console. To run a command, type a forward slash. There are many commands to learn.

Variables
How to select	What it is
~	Inserts the current axis position when used inside a position argument. This can be used so you don't need to know your coordinates, or if a command block is likely not going to be in a set location. You may add a number after it, positive or negative, to add an offset, so ~~-3~ is 3 blocks below, and ~~3~ is 3 blocks above. ~ 3 ~ would be an absolute y=3. ~3~ would not be invalid, however, as there is only an x and y, but not a z.
@p	The closest player.
@a	All players.
@r	Random player.
@e	All entities.
@s	Self. Note that this does not work on command blocks unless using the /execute command.

The @ selectors also allow finer tuning, like this: @r[r=10,tags=alive] checks for a random player within ten blocks, with the "alive" tag (set with /tag). All of them are:

r: range. Note that this is a spherical radius!
rm: minimum range. Note that this is a spherical radius! Any entity closer than this radius will not be included.
l & lm: Level and minimum level, respectively.
c: count. The maximum number of entities that can be returned.
m: gamemode. Only works on players. Supported values are: creative, survival, adventure, spectator.
name: Checks the name of the entity matches this value.
tags: checks if a tag exists on that entity.
type: checks its identifier matches. The identifier is usually a snake_case (all lowercase, underscores instead of spaces) version of its name.
family: Checks if a entity is part of a particular entity family. Examples include undead, zombie, monster, and inanimate.
x / y / z: If a coordinate matches.
dx / dy / dz: distance from x / y / z. Example, an x of 0 and dx of 5 will only check x=0 to x=5. Set dx to -5 to reverse this, or x to -5 and dx to 10 to check between x=-5 and x=5. If one of these parameters are not set, and are used, a value of 0 is assumed.