>>24
cat -- -u
http://pubs.opengroup.org/onlinepubs/009604499/basedefs/xbd_chap12.html
Guideline 10:
The argument -- should be accepted as a delimiter indicating the end of options. Any following arguments should be treated as operands, even if they begin with the '-' character. The -- argument should not be used as an option or as an operand.
--
And if you're wondering "what if I have a file named '--'", that would be
cat -- --.
>>17-22
These are going to be slow as fuck because they're all reading and writing one char at a time.