xxd(1) - make a hexdump or do the reverse
-a | -autoskip
       toggle autoskip: A single '*' replaces nul-lines.  Default off.
-b | -bits
       Switch  to  bits  (binary  digits)  dump, rather than hexdump.  This option writes octets as eight
       digits "1"s and "0"s instead of a normal hexadecimal dump. Each line is preceded by a line  number
       in  hexadecimal and followed by an ascii (or ebcdic) representation. The command line switches -r,
       -p, -i do not work with this mode.
-c cols | -cols cols
       format <cols> octets per line. Default 16 (-i: 12, -ps: 30, -b: 6). Max 256.
       Change the character encoding in the righthand column from ASCII to EBCDIC.  This does not  change
       the hexadecimal representation. The option is meaningless in combinations with -r, -p or -i.
-g bytes | -groupsize bytes
       separate  the  output  of  every  <bytes> bytes (two hex characters or eight bit-digits each) by a
       whitespace.  Specify -g 0 to suppress grouping.  <Bytes> defaults to 2 in normal  mode  and  1  in
       bits mode.  Grouping does not apply to postscript or include style.
-h | -help
       print a summary of available commands and exit.  No hex dumping is performed.
-i | -include
       output  in  C  include  file style. A complete static array definition is written (named after the
       input file), unless xxd reads from stdin.
-l len | -len len
       stop after writing <len> octets.
-p | -ps | -postscript | -plain
       output in postscript continuous hexdump style. Also known as plain hexdump style.
-r | -revert
       reverse operation: convert (or patch) hexdump into binary.  If not writing to stdout,  xxd  writes
       into  its  output  file without truncating it. Use the combination -r -p to read plain hexadecimal
       dumps without  line  number  information  and  without  a  particular  column  layout.  Additional
       Whitespace and line-breaks are allowed anywhere.
-seek offset
       When used after -r: revert with <offset> added to file positions found in hexdump.
-s [+][-]seek
       start  at <seek> bytes abs. (or rel.) infile offset.  + indicates that the seek is relative to the
       current stdin file position (meaningless when not reading from stdin).  - indicates that the  seek
       should  be  that  many  characters  from  the  end of the input (or if combined with +: before the
       current stdin file position).  Without -s option, xxd starts at the current file position.
-u     use upper case hex letters. Default is lower case.
-v | -version
       show version string.