/function

Syntax

/function <name>

/function <name> <arguments>

/function <name> with (block <source>|entity <source>|storage <source>) [<path>]

Argument	Kind of value	What to type
<name>	Function	The id of the function, for example my_pack:setup, or a function tag starting with #.
<arguments>	Data in braces	The macro values as a data compound, for example {name:"Alex"}.
<source>	Block position	For with: the block position, the single entity or the storage id the macro values are read from.
<path>	Data path	For with: the data path of the compound that holds the macro values. Optional.

Permission level	2: operators, worlds with cheats on, command blocks and functions
Works in	Operators on multiplayer servers, singleplayer worlds with cheats enabled, and command blocks and functions.
Result	Reports "Running function" with the function id. If a function returns a value, it also reports "Function ... returned ...", and that value is the number /execute store saves. When several functions of a tag return values, the result is their sum.
Function tags	A name starting with # runs every function in that function tag. If the tag contains no functions, the command fails with "Can't find any functions".
Arguments for macros	Functions that contain macro lines need values. Write them as a data compound after the name, or read them from a block, entity or storage with the with sub-command.
with	with block, with entity and with storage take the values from existing data. An optional path picks a part of that data, which must be a compound; otherwise the command fails with "Expected Compound".
Permission inside functions	Commands inside the function run with permission level 2 at most, even if the function is started by someone with a higher level, and they do not print their own output.
Missing values	If a macro value is missing or a macro line becomes an invalid command, the command fails with "Failed to instantiate function".

/function my_pack:setup

Runs the function setup from the data pack namespace my_pack.

/function #my_pack:start_round

Runs every function in the function tag start_round.

/function my_pack:greet {name:"Alex"}

Runs the function greet and fills its macro value name with Alex.

/function my_pack:greet with storage my_pack:settings greeting

Runs the function greet with the macro values stored under greeting in the storage my_pack:settings.