 --[[ 
Hello!

I was bored, and decided to set my Lua skill up for a test, so I did the unthinkable:
I coded an entire operating system in Lua!
(Due to legal reasons, I have to tell you that this is a text-based operating system.)

It isn't that strong, so it can't do much. It's supposed to be like MS-DOS 1.25 if you've ever used that.
This is a text-based compiler, so I can't add in any GUI. (I can, but I'm trying to finish this before the holidays end.)
Input commands in using the STDIN. Type "help" to show a list of all the defined commands.

There are some secret commands not listed in the help command, though.
I strongly refuse you scroll down unless you want to spoil the fun of finding the secret commands.

You do have to restart the compiler after every command, but I'm trying to fix that.

Hope you enjoy!
(Made by Kacper)
]]

































local command = io.read("l")

local function starts_with(command, word)
  local first_chars, rest = string.sub(command, 1, string.len(word)), string.sub(command, string.len(word) + 1)
  return first_chars == word and rest ~= ""
end

if command == "help" then
  print("Available commands:")
  print("  help: Show this help message")
  print("  dir: Shows a list of all the directories.")
  print("  remove: Deletes a file.")
  print("  memory: Check the memory value on a specific location.")
  print("")
  print("Available subcommands:")
  print("  ner: Prevents a command from returning an error.")
  print("  move: Moves a file from one drive to another.")
elseif command == "dir" then
  print("Directories for L:/")
  print("  LUA: 4231 bytes")
  print("  SYS: 42462 bytes")
  print("    P: 1204 bytes")
  print("    CMD: 31233 bytes")
elseif command == "ner remove CMD" then
  print("Type in CMD file size to remove.")
elseif command == "ner move CMD" then
  print("Type in CMD file size to remove.")
elseif command == "ner remove CMD 31233" then
  print("Error 0x6: Critical process removed.")
elseif command == "remove CMD" then
  print("0x1: Cannot remove critical file.")
elseif command == "move CD" then
  print("0x2: Cannot move critical file.")
elseif command == "secret" then
  print("Don't tell anyone about this, but MR. Skinglebob will do the skingamabiddle on you in exactly 5 hours, 13 minutes and 26 seconds.")
elseif command == "the meaning of life" then
  print("42")
elseif command == "the meaning of death" then
  print("-42")
elseif command == "memory 0x1993" then
  print("LUA DOS")
  print("    1.0  ")
  print("")
  print("Kacper Misztal: Helped create the DOS.")
  print("Kor: Criticized the entire thing.")
elseif starts_with(command, "memory 0x") then
  print("0x5: Restricted memory location")
else
  print("0x0: Unknown command.")
end

created 5 months ago by Kacper Misztal

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About Lua

Lua is a light weight embeddable scripting language which is built on top of C. It is used in almost all kind of applications like games, web applications, mobile applications, image processing etc. It's a very powerful, fast, easy to learn, open-source scripting language.

Syntax help

Variables

By default all the variables declared are global variables
If the variables are explicitly mentioned as local then they are local variables.
Lua is a dynamically typed language and hence only the values will have types not the variables.

Examples

-- global variables
a = 10

-- local variables

local x = 30

Value Type	Description
number	Represents numbers
string	Represents text
nil	Differentiates values whether it has data or not
boolean	Value can be either true or false
function	Represents a sub-routine
userdata	Represents arbitary C data
thread	Represents independent threads of execution.
table	Can hold any value except nil

Loops

1. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition)
do
--code
end

2. Repeat-Until:

Repeat-Until is also used to iterate a set of statements based on a condition. It is very similar to Do-While, it is mostly used when you need to execute the statements atleast once.

repeat
   --code
until( condition )

3. For:

For loop is used to iterate a set of statements based on a condition.

for init,max/min value, increment
do
   --code
end

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increase re-usuability and modularity.

optional_function_scope function function_name( argument1, argument2, argument3........, argumentn)
--code
return params with comma seperated
end