I could essentially edit the file in place without having to create a temporary file.

Generally this isn't possible. You can only overwrite the existing parts of the log, not slice them out of the file. The normal way to do what you want is to process your input records as shown here by me and several of the other monks and then process them and output them to the new file, and then delete the old file. You can't really remove from the beginning of a file while something is writing to the end.

Anyway, glad to help. :-)