command block 

A command block is a block that can execute commands. Because it cannot be obtained in Survival mode without cheats, it is primarily used on multiplayer servers and in custom maps.

Command blocks are not available in the Creative inventory. It can either be obtained by using the pick block control, or by using various commands, such as /give @s minecraft:command_block, or /setblock ~ ~ ~ minecraft:command_block.

Command blocks also cannot be broken in Survival mode without operator permissions, are not flammable, cannot be moved by pistons, and have the same blast resistance as bedrock.

To enter a command in a command block, use the Use Item control on the command block to open the command block graphical user interface. The GUI opens only if the player is in Creative mode and has the proper permissions. In singleplayer, cheats must be enabled to edit them; in multiplayer, they can be edited only by operators in Creative.

Command blocks are redstone mechanisms and can be activated by:
- An adjacent active power component: e.g., a redstone torch, block of redstone, daylight sensor, button etc.
- An adjacent powered block (for example, an opaque block with an active redstone torch under it)
- A powered redstone comparator or redstone repeater facing the mechanism component
- Powered redstone dust pointing at the command block (or on top of it) or directionless.

When activated, a command block tries to execute its command.

If you mostly play survival mode, and you're thinking "that sounds a lot like cheating", then you're right – which is why command blocks aren’t available in survival mode. They're a feature that we built specifically for creative mode, and for adventure mode mapmakers. Jeb announced their existence in a tweet in July 2012, and they were added to the game in version 1.4.2 – the Pretty Scary Update, which also added spooky anvils, creepy flowerpots and terrifying carrots on sticks.

command block by sun-uv-a-bee-atch January 3, 2020

/give @s command_block 1 

gave one command block to steve.

steve:/give @s command_block 1
command block: hippity hoppity your slot is now my property.

/give @s command_block 1 by ISSDefinitions August 11, 2021