ComputerCraft

Automatic startup script

Write a startup.lua that runs automatically on every boot — no need to type anything after placing the computer.

Category: ComputerCraft Difficulty: Beginner Time: ~10 min

What you will end up with

A CC:Tweaked computer that, on every boot, automatically clears the screen, prints a welcome message, and displays the current time. You can then extend the script to do anything you like — run programs, check inventories, or start a monitor display.

What you need

A Computer or Advanced Computer (from CC:Tweaked)
Basic familiarity with the CC:Tweaked terminal (typing commands)

CC:Tweaked automatically runs a file called startup or startup.lua from the root of the computer's filesystem on every boot. This is the standard way to automate a computer without any extra configuration.

Step by step

Place a Computer block and right-click it to open the terminal.
Create the startup file using the built-in editor:
edit startup.lua
Type the following program into the editor:
-- startup.lua -- Runs automatically on every boot term.clear() term.setCursorPos(1, 1) print("=== AIVONI MC ===") print("") print("Server: mc.aivoni.eu") print("Time: " .. textutils.formatTime(os.time(), true)) print("") print("Computer ready.")
Save and exit: press Ctrl, select Save, then press Ctrl again and select Exit.
Reboot the computer to test:
reboot
The script should run immediately on startup.

How it works

When CC:Tweaked boots a computer it looks for a file named startup or startup.lua in the root directory and executes it automatically. No special registration is needed — just the file name.

The script above uses a few standard CC:Tweaked APIs:

term.clear() — clears the terminal screen
term.setCursorPos(1,1) — moves the cursor to the top-left corner
os.time() — returns the current in-game time
textutils.formatTime() — formats the time as a readable string

Running another program from startup

If you want the startup script to launch another program (for example your monitor display), use shell.run() at the end of startup.lua:

-- At the end of startup.lua, launch another program:
shell.run("my_program")

shell.run() runs the program and waits for it to finish before continuing. If your program runs in an infinite loop, the startup script will stay in that loop — which is usually exactly what you want for a permanent display or monitor program.

Editing startup after a reboot

If the startup script runs an infinite loop, you can interrupt it by holding Ctrl + T for about two seconds. This terminates the running program and returns you to the shell, where you can edit the file again.

Full example — startup with monitor launch

-- startup.lua — boots into the monitor display program

term.clear()
term.setCursorPos(1, 1)
print("Booting AIVONI monitor...")
os.sleep(0.5)
shell.run("monitor_display")

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