Thread: Writing hex to a file

Hello everyone, I'm in need of your help. I've always thought that files were made up of bytes which range from 0 to 255 in decimal value. But when reading the values of some mp3's and other audio files I found myself sometimes getting negative numbers like -29 or hex that start off 'FFFFFF' as in FFFFFF0A. I want to be able to edit files with such values on that level but I have no knowledge of how to write these values into a file. Assuming ** is a hex value the most I know is:

Code:

 
myfile << '\x**'

I can write from 00 to FF in hex but not outside that range. If there is anyone who can help me I would greatly appreciate them showing me how to do it.

Thanks a lot.

Thanks Salem. I get why I'd be doing that but I still have no idea how to enter negative values. Like the line of code I put above, what would I have to write?

Thanks Mats, I'm pretty sure I do want to though. Do you know how I can do that?

printf "%b" "\x$(printf "%x" 10)">a

ref to：:how to handle hex values in bash ? - Usenet Forums

Bash? From Linux? I'm sure there is one for vista but I'd have to work all the way backwards and ATTEMPT to learn how to use it well as opposed to the one line of code I've been asking for from the beginning. I'm pretty much a noob, like a third world child who has just learnt how to read.

For me, these answers only lead to more questions. I can't help but feel sexually frustrated right now.

Thanks Mats