Lua reference

What a Lua Box program sees besides standard Lua.

Functions of the box

Function	Does
print(...)	Writes a line into the box's output.
sleep(seconds)	Pauses the program. A program that never sleeps is stopped, see Settings and commands.
require(name)	Runs name.lua from the box once and returns what it returned.
files.list()	The names of all files of the box, main.lua included, sorted.
files.read(name)	The whole file as a string. An error if the box has no such file.
files.lines(name)	An iterator over the lines of the file, without line ends.
os.time(kind), os.date(format, time), os.clock(), os.day(kind), os.epoch(kind)	Clock functions as in CC: Tweaked. kind is "ingame" (default), "utc" or "local".
textutils.formatTime(time, twentyFour)	A time of day as text.

Programs cannot write files.

The network

Function	Does	Returns
network.list()		the names of all machines the box reaches
network.findByName(name)		the machine's handle, or nil
network.find(type)	type is a full id such as "minecraft:sign", or just "sign"	a list of handles
network.version()		a number that grows on every change; poll it to notice new machines
engine	The one Billboard Engine of the network, if the Billboard Engine mod is installed.

print(table.concat(network.list(), ", "))    -- sign_1, redstone_port_1
local sign = network.findByName("sign_1")    -- nil if there is none
for _, s in ipairs(network.find("sign")) do s.clear() end

Every machine

Each handle has:

Function	Does	Returns
getName()		the name
setName(name)	1 to 32 letters, digits, _ or -	true, or nil + the reason
getType()		the type, such as "minecraft:sign"

and the machine's own functions. A handle to a machine that was broken or cut off raises client "sign_1" is not reachable, and works again when the machine is back. Some machines answer later; the program then waits for them.

Claiming

Machines that one program should drive at a time offer claim(), release() and isClaimed():

• claim() returns true, or false plus who holds it. It never waits.
• release() returns true, or false if this program did not hold it.
• isClaimed() returns false, or true plus who holds it.
• The claim ends by itself when the program ends or is stopped, or its box is gone.

The Redstone Port works this way; so do the Billboard Engine and the Typewriter.

Signs

Vanilla signs and hanging signs are machines of the type minecraft:sign. back is optional and means the back of the sign; the default is the front.

Function	Does
getLines(back)	The four lines.
getLine(n, back)	Line 1 to 4.
setLine(n, text, back)	Sets one line, up to 80 characters.
setLines({...}, back)	Sets all lines.
clear(back)	Empties the sign.

Redstone Port

claim(), release(), isClaimed(), setOutput(side, level), getOutput(side), getInput(side) and getBlock(side): see Redstone Port.