bios:206: [string "startup"]:13: '=' expected

i am running this code

function start()
print("password required to open")
a = read()
if a == "password" then
print ("accewss Granted")
rs.setOutput("right.true)
else
print ("access denied")
rs.setOutput("left", true)
sleep(3)
os.shutdown

end

what am i doing wrong? i gives me a bios:206: [string "startup"]:13: '=' expected when i start up please help!

After formatting your code, your error wasn't hard to track down:

function start()
 print("password required to open")
 a = read()
 if a == "password" then
  print ("Access Granted") --Minor spelling error
  rs.setOutput("right", true) --Corrected code, unfinished string, nil function call: rs.setOutput("right", true). I did not even notice this until posting it in the forum, as the rest of the program became green. right.true is not a function, you put a period instead of a comma. Lastly, forgot to close the string, "right", by adding a quotation mark at the end.
 else
  print ("Access Denied") -- Capitalized words
  rs.setOutput("left", true)
  sleep(3)
  os.shutdown
 end --Forgot to close 'if' statement, or function. In short, you left out one 'end'.
end

Also, since you defined this as a function, you'll need to add:

start()

At the end of all the code to call the function or else after the computer starts up, it'll just go to the shell and not do anything.

os.shutdown() instead of os.shutdown.