Locks are computer programs used to lock doors (usually iron doors to prevent forced entry). The most common lock programs require a password in order to gain entry.

The most common lock code is this (Thanks to Hydrogen on Minecraft Forums) :

1. --Title: TangentLockLite
2. --Version: 1
3. --Last Revised: N/A
4. --Last Revised By: N/A
5. --Author: TangentDelta (alias Hydrogen)
6. --Platform: ComputerCraft LUA Virtual Machine
7. --Notes: Please don't claim this as yours, give me credit!
9. password = "hello" --this is your password to "unlock" the door
11. print "TangentLockLite Ver. 1" --tells you what version it is
12. write "Password: " --puts a pretty "Password: " on the screen, so you know what you're doing
13. input = read("*") --make a prompt where you can type stuff in, and stores it to the "input" variable EDIT: By DJZ07728. I made it so text you type is hidden.
14. if input == password then --if what you type in is equal to your password, it does the following
15. redstone.setOutput ("back", true) --makes the back of the computer turn on a redstone pulse
16. sleep (5) --pause for 5 seconds
17. os.shutdown() --makes the computer turn off
18. else --but if the password isn't correct
19. print "Incorrect Password" --let's you know that the password is wrong
20. sleep (2) --pause for 2 seconds
21. os.shutdown() --makes the computer turn off

22. end --the end of the program