I recently needed to write a Perl script that had to replace a byte in position 148 of a large binary file. The inserted byte was dynamic, depending on the file's contents.

I read in and wrote out the first 148 characters of the file(using read and print), inserted my new character, and then used `/usr/xpg4/bin/tail -c +150 $infile >> $outfile`; to append the remainder of the file.

This worked fine, but I was wondering if there is a better way to do it. The code does not need to be portable, so that's not an issue. I was under some pressure time-wise to get this going so this seemed to be the quickest way to get it to work. Is there a good and efficient way in perl to simply read in and write out large amounts of binary (not text) data?

Thanks in advance, and Cheers!

In reply to Copying binary data efficiently by mildside

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