I have a file used in customized session.
I want to rename the file once the file is processed.
The process uses seq.* functions such as seq.open, seq.gets, seq.puts, and seq.close.
I have searched for "seq", "rename", and "change file name" but to no avail.

Finally, this link http://www.baanboard.com/baanboard/showpost.php?p=88192&postcount=3 pretty much answers the question.
In this case, I use
file.mv(old.file.name, new.file.name)
and it works like a charm.