OKAY----

Here's what I must do.
I have two files. I need to compare the two files such as with the diff command. I am adding FILENEW to FILEOLD

If fields $1, $2, $5, and 6 are the same, then I don't want to add FILENEW records to FILEOLD.
If they are not, then append the lines.

Is this possible in the UNIX scripting world? It seems that this could be done in AIX. I also have Perl as a last resort. Looking hard, wondered if anyone has done something like this before.