Hi and welcome to LinuxQuestions!
I wonder what is the purpose of this, anyway you can try the
dd command (be careful if you're not experienced with it). For example:
Code:
dd if=xxx.r count=1 ibs=1 skip=18 2>/dev/null
will send the 19th byte to the standard output, so that you can store it in a variable. If you want to redirect it to a file, add the
of predicate:
Code:
dd if=xxx.r of=file.out count=1 ibs=1 skip=18 2>/dev/null
Hope this helps.