Getting "error ":1: "do" expected", even though "do" already exists

So I was making a program to control my redpower2 tunnel bore (I'm using computercraft computers), and when I run this program, I get the error, "error [something here] :1: "do" expected". I already have a "do" on line 1 though, so I'm not sure what to do…
Essentially what this program is supposed to do is, whenever it receives a redstone signal from the front, it starts the frame motors with redstone signals.

while redstone.getInput("front") = true do
  redstone.setOutput("back", true)
  sleep(0.4)
  redstone.setOutput("back", false)
  sleep(1.44)
  redstone.setOutput("left", true)
  redstone.setOutput("right", true)
  sleep(1.44)
  redstone.setOutput("left", false)
  redstone.setOutput("right", false)
end

To check if a variable is equal to something else, you have to put "==" instead of "=".

To compare you must put == instead of =
Edit: ninja'd

Ninetainedo, on 05 April 2013 - 01:59 PM said:

To check if a variable is equal to something else, you have to put "==" instead of "=".

Thank you!