Create a new version of paste:

  --[[
  ------------------------

  Originally made by 'Engineer' on the ComputerCraft forums
  http://www.computercraft.info/forums2/index.php?/topic/11484-/

  Edited by DeliciousJaffa to fix bugs, add documentation and add a whole load of new functionality
  http://twitter.com/DeliciousJaffa

  ------------------------

  Current version: 1.0.1.3

  Documentation:
  1. Installation
    Run the following commands:
      pastebin get JW4uj2Jw startup
      reboot

  2. Usage
    "startup auto list" - This command will list all auto updating programs
    "startup auto add <paste bin code> <program>" - This command will add a program to check for updates from a pastebin page
    "startup auto remove <program>" - This will remove a program from the auto update list by it's name (also known as it's command)
    "startup auto reset" - This will reset the auto update list to the current defaults
    
    "startup set <program>" - This command will set a program to be launcher after update checking when the computer restarts
      (or when the chunk becomes loaded again)
    "startup unset" - This will wipe the startup so that no program is ran automatically.

    "startup update" - This command will check if the code at the specified pastebin id
      is different from the named program, if it is, it'll automatically download the update before anything else
  
  3. Preinstalled programs
    This auto-updater installs 2 programs by default.
      - "EpicMine" by Princetommen http://pastebin.com/6qmBBLpz
        Mines out tunnels or an area
      - "Attack" by DeliciousJaffa http://pastebin.com/vNNYrHUp
        Attacks mobs forever and drops items
  ------------------------
  ]]

local tArgs = { ... }
local autoFile = "/startup-updatelist"
local prefFile = "/startup-prefs"
local defaultsPbinCode = "B2jBQTU2"

function usage()
  print( "Usage:" )
  print( "- startup auto list" )
  print( "- startup auto add <pastebin code> <program>" )
  print( "- startup auto remove <program>" )
  print( "- startup auto reset" )
  print( "- startup set <program>" )
  print( "- startup unset" )
  print( "- startup update" )
  print( "See the documentation for more information")
end

function getPastebin( code )
  local response = http.get(
    "http://pastebin.com/raw.php?i=" .. textutils.urlEncode( code )
  )
  if response then
    local contents = response.readAll()
    local file = fs.open( code, "w" )
    file.write( contents )
    file.close()
    return true, contents
  else
    return false
  end
end

function setDefaults()
  if fs.exists( autoFile ) then
    fs.delete( autoFile )
  end
  local file = fs.open( autoFile, "w" )
  local condition, raw = getPastebin(defaultsPbinCode)
  fs.delete(defaultsPbinCode)
  local default = textutils.unserialize(raw)
  local tPrograms = {}
  if condition == true then
    tPrograms = default
    file.write( textutils.serialize(tPrograms))
    file.close()
    print("Default autoupdate list installed")
  else
    print("Failed to obtain the default update list")
  end
end

function update()
  if fs.exists( autoFile ) then
    local file = fs.open( autoFile, "r" )
    local handler = file.readAll()
    file.close()
    local tPrograms = textutils.unserialize( handler )
    if type( tPrograms ) == "table" then
      for i = 1, #tPrograms do
        local condition, content = getPastebin( tPrograms[i][1] )
        if condition then
          local reader = "needsupdateornot"
          if fs.exists(tPrograms[i][2]) then
            local installed = fs.open(tPrograms[i][2], "r")
            reader = installed.readAll()
            installed.close()
          end
          if reader ~= content then
            fs.delete( tPrograms[i][2] )
            fs.move( tPrograms[i][1], tPrograms[i][2] )
            print( "Updated " .. tPrograms[i][2] .. " succesfully!" )
          else
            print( "No update needed for: "..tPrograms[i][2] )
            fs.delete( tPrograms[i][1] )
          end
        else
          print( "Update for " .. tPrograms[i][2] .. " unsuccesfull!" )
        end
      end
    end
  end
  print("Update check completed")
end

if not fs.exists( autoFile ) then
  setDefaults()
end

local sCommand = "noCommand"
if #tArgs == 0 then
  update()
  print("See documentation for commands (pastebin page)")
  if turtle then
    if os.getComputerLabel() then
      print(os.getComputerLabel() .. " reporting for duty with " .. turtle.getFuelLevel() .. " fuel")
    else
      print("Reporting for duty with " .. turtle.getFuelLevel() .. " fuel")
    end
  else
    if os.getComputerLabel() then
      print(os.getComputerLabel() .. " reporting for duty!")
    end
  end
  if fs.exists( prefFile ) then
    local file = fs.open( prefFile, "r" )
    local startupname = file.readAll()
    if fs.exists(startupname) then
      print("Launching startup program")
      shell.run(startupname)
    else
      print("Startup program could not be found.")
    end
  end
elseif #tArgs > 4 then
  usage()
else
  if string.lower( tArgs[1] ) == "manual" and tArgs[3] then
    sCommand = "manual"
  elseif string.lower(tArgs[1]) == "auto" then
    if string.lower( tArgs[2] ) == "remove" and tArgs[3] then
      sCommand = "auto_getoff"
    elseif string.lower( tArgs[2] ) == "add" and tArgs[4] then
      sCommand = "auto_add"
    elseif string.lower( tArgs[2] ) == "list" then
      sCommand = "auto_list"
    elseif string.lower( tArgs[2] ) == "reset" then
      setDefaults()
    else
      usage()
    end
  elseif string.lower(tArgs[1]) == "set" then
    sCommand = "setstartup"
  elseif string.lower(tArgs[1]) == "unset" then
    sCommand = "delstartup"
  elseif string.lower(tArgs[1]) == "update" then
    update()
  else
    usage()
  end
end

if not http then
  print( "HTTP not enabled" )
  print( "Enable this in the config" )
  error()
end

if sCommand == "manual" then
  local sFile = tArgs[3]
  local sCode = tArgs[2]
  if not fs.exists( sFile ) then
    local rAnswer, download
    term.clear()
    term.setCursorPos( 1,1 )
    print( "File doesn't exist!\nStill download " .. sCode .. " to "..sFile.." ? (Y/N)" )
    while true do
      local evt, key = os.pullEvent("char")
      if key == "y" then
        download = true
        break
      elseif key == "n" then
        download = false
        break
      end
    end
    if download then
      if getPastebin( sCode ) then
        fs.move( sCode, sFile )
        print( "Succesfully downloaded " .. sCode .. " as " .. sFile )
      elseif not getPastebin( sCode, sFile ) then
        print( "Could not download " .. sCode .. " from pastebin.com" )
      end
    end
  else
    if getPastebin( sCode ) then
      fs.delete( sFile )
      fs.move( sCode, sFile )
      print( "Succesfully updated " .. sFile )
    elseif not getPastebin( sCode ) then
      print( "Could not update " .. sFile .. " with " .. sCode )
    end
  end
elseif sCommand == "auto_list" then
  if not fs.exists( autoFile ) then
    print( "Nothing is added yet" )
  else
    local file = fs.open( autoFile, "r" )
    local reader = file.readAll()
    file.close()
    local tPrograms = textutils.unserialize( reader )
    term.clear()
    term.setCursorPos( 1,1 )
    print( "Pastebin Code:    Program Name:" )
    if type( tPrograms ) == "table" then
      for i = 1, #tPrograms do
        term.setCursorPos( 1, i + 2 )
        write( tPrograms[i][1] )
        term.setCursorPos( 19, i + 2 )
        write( tPrograms[i][2] )
        term.setCursorPos( 1, i + 3 )
      end
    else
      print( "None              None")
    end
  end
elseif sCommand == "auto_add" then
  local sCode = tArgs[3]
  local sFile = tArgs[4]
  if sFile and getPastebin( sCode ) then
    fs.delete( sCode )
    local file = fs.open( autoFile, "r" )
    local handler = file.readAll()
    file.close()
    local tPrograms = textutils.unserialize( handler )
    if type( tPrograms ) ~= "table" then
      local file = fs.open( autoFile, "w" )
      tPrograms = {}
      file.write( textutils.serialize( tPrograms ) )
      file.close()
    end
    local codeintable = false
    for i = 1, #tPrograms do
      if tPrograms[i][2] == sFile then
        codeintable = true
      end
    end
    if codeintable == false then
      table.insert( tPrograms, { sCode, sFile } )
    end
    fs.delete( autoFile )
    file = fs.open( autoFile, "w" )
    file.write( textutils.serialize( tPrograms ))
    file.close()
    if codeintable == false then
      print("Succesfully added " .. sFile .. " to the update list." )
    else
      print("Please remove " .. sFile .. " from the list before adding a new code for it")
    end
    update()
  elseif not getPastebin( sCode ) then
    print( "Your pastebin code is invalid" )
  end
elseif sCommand == "auto_getoff" then
  local sFile = tArgs[3]
  local file = fs.open( autoFile, "r" )
  local handler = file.readAll()
  file.close()
  local tPrograms = textutils.unserialize( handler )
  for i = 1, #tPrograms do
    if tPrograms[i][2] == sFile then
      table.remove( tPrograms, i)
      table.remove( tPrograms, i)
      break
    end
  end
  fs.delete( autoFile )
  file = fs.open( autoFile, "w" )
  file.write( textutils.serialize( tPrograms ) )
  file.close()
  print( "Succesfully removed " .. sFile .. " from the auto update list." )
elseif sCommand == "setstartup" then
  local file = fs.open( prefFile, "w" )
  file.write( tArgs[2] )
  file.close()
  print("" .. tArgs[2] .. " will now open on startup")
elseif sCommand == "delstartup" then
  if fs.exists(prefFile) then
    fs.delete(prefFile)
    print("This computer will no longer auto launch a program on startup")
  end
    print("Error: No launch program set")
end