function loadfile(p) -- reads file *p* and returns a function if possible
 local f = fs.open(p,"rb")
 local c = f:read("*a")
 f:close()
 return load(c,p,"t")
end
function runfile(p,...) -- runs file *p* with arbitrary arguments in the current thread
 return loadfile(p)(...)
end
function os.spawnfile(p,n,...) -- spawns a new process from file *p* with name *n*, with arguments following *n*.
 local tA = {...}
 return os.spawn(function() computer.pushSignal("process_finished", os.pid(), pcall(loadfile(p), table.unpack(tA))) end,n or p)
end
_G.libs = {computer=computer,component=component}
function require(f) -- searches for a library with name *f* and returns what the library returns, if possible
 local lib = os.getenv("LIB") or "/boot/lib"
 for d in lib:gmatch("[^\n]+") do
  if fs.exists(d.."/"..f) then
   _G.libs[f] = runfile(d.."/"..f)
  elseif fs.exists(d.."/"..f..".lua") then
   _G.libs[f] = runfile(d.."/"..f..".lua")
  end
 end
 if _G.libs[f] then
  return _G.libs[f]
 else
  error("library not found: "..f)
 end
end