Script for mass updates

[Nick Milas]

Hello,

Does anyone have a ready-made script (e.g. bash) that would do the 
following:

 Loop on all entries in the ou=people branch where ou <> "system" {
   If attribute DisplayName does not exist{
      Set DisplayName to the value of attibute cn
  }
 }

I could do it with a bit of work, but it's urgent.

Any help will be appreciated!

Thanks in advance,
Nick