Comment 7 for bug 1084885

-nocpp is being used in gdm/lightdm quite deliberately (not blindly/not a bug). We don't want to penalize the vast majority of users at every boot with wasting the cpp call (which is quite expensive) for the tiny fraction of power users who actually use this.

A check like Derek proposed sounds fine to me, but let's avoid grep please. Posix shell can do substring match just fine:

  test "${string#*$word}" != "$string" && echo "$word is in $string"