in reply to help needed in unicode files
Yes. File::BOM will do this for you. Not that you should be writing a BOM for UTF-8 (kind of difficult to get confused about the byte order on one byte wide characters), but I expect you are dealing with (broken) MicroSoft apps.
Updated: You should really read the documentation. There are several examples in it of how to do what you appear to be asking for. Here's one:
open(HANDLE, '<:via(File::BOM)', $filename)
open(HANDLE, '>:encoding(UTF-8):via(File::BOM)', $filename)
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