Convert hexadecimal dump to binary

The command xxd with the -r option can do that.

Sample usage:

   1 nano test.hex #fill it with 41 41 41 42 31 31 33 0D 0A and save
   2 xxd -r -p test.hex | hexdump -C # to view the conversion
   3 xxd -r -p test.hex test.bin # store the conversion
   4