If you work with the command line you've most likely
used hexdump or od to dump binary files,
but what do you do if you have a hex dump of something
and you want to create the binary version of the data?
Assuming your needs aren't too complex, the answer may be xxd.
You can use xxd to dump binary files just like hexdump and od,
but you can also use it to do the reverse: turn a hex dump back into binary.