xxd - make a hexdump or do the reverse.


   xxd -h[elp]
   xxd [options] [infile [outfile]]
   xxd -r[evert] [options] [infile [outfile]]


   xxd  creates a hex dump of a given file or standard input.  It can also
   convert a hex dump back to its original binary form.  Like  uuencode(1)
   and  uudecode(1)  it allows the transmission of binary data in a `mail-
   safe' ASCII representation,  but  has  the  advantage  of  decoding  to
   standard  output.   Moreover,  it  can  be  used to perform binary file


   If no infile is given, standard input is read.  If infile is  specified
   as  a  `-'  character,  then input is taken from standard input.  If no
   outfile is given (or a `-' character is in its place), results are sent
   to standard output.

   Note  that  a  "lazy" parser is used which does not check for more than
   the first option letter, unless the option is followed by a  parameter.
   Spaces  between  a single option letter and its parameter are optional.
   Parameters to options can be specified in decimal, hexadecimal or octal
   notation.  Thus -c8, -c 8, -c 010 and -cols 8 are all equivalent.

   -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.

   -E | -EBCDIC
          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.

   -e     Switch to little-endian hexdump.  This option treats byte groups
          as words in little-endian byte order.  The default grouping of 4
          bytes  may  be  changed  using  -g.  This option only applies to
          hexdump, leaving the ASCII (or EBCDIC) representation unchanged.
          The command line switches -r, -p, -i do not work with this mode.

   -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, 4 in
          little-endian 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.

   -o offset
          add <offset> to the displayed file position.

   -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.


   xxd -r has some builtin magic while evaluating line number information.
   If  the  output  file is seekable, then the linenumbers at the start of
   each hexdump line may be  out  of  order,  lines  may  be  missing,  or
   overlapping.  In these cases xxd will lseek(2) to the next position. If
   the output file is not seekable, only gaps are allowed, which  will  be
   filled by null-bytes.

   xxd -r never generates parse errors. Garbage is silently skipped.

   When  editing hexdumps, please note that xxd -r skips everything on the
   input line after reading enough columns of hexadecimal data (see option
   -c).  This  also means, that changes to the printable ascii (or ebcdic)
   columns are always ignored. Reverting a  plain  (or  postscript)  style
   hexdump  with  xxd  -r  -p  does  not  depend  on the correct number of
   columns. Here  anything  that  looks  like  a  pair  of  hex-digits  is

   Note the difference between
   % xxd -i file
   % xxd -i < file

   xxd  -s +seek may be different from xxd -s seek, as lseek(2) is used to
   "rewind" input.  A '+' makes a difference if the input source is stdin,
   and  if  stdin's  file  position is not at the start of the file by the
   time xxd is started and given its input.  The  following  examples  may
   help to clarify (or further confuse!)...

   Rewind  stdin before reading; needed because the `cat' has already read
   to the end of stdin.
   % sh -c "cat > plain_copy; xxd -s 0 > hex_copy" < file

   Hexdump from file position 0x480 (=1024+128)  onwards.   The  `+'  sign
   means "relative to the current position", thus the `128' adds to the 1k
   where dd left off.
   % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +128 >  hex_snippet"
   < file

   Hexdump from file position 0x100 ( = 1024-768) on.
   % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +-768 > hex_snippet"
   < file

   However, this is a rare situation and the use of `+' is rarely  needed.
   The  author  prefers  to  monitor  the  effect of xxd with strace(1) or
   truss(1), whenever -s is used.


   Print everything but the first three lines (hex 0x30 bytes) of file.
   % xxd -s 0x30 file

   Print 3 lines (hex 0x30 bytes) from the end of file.
   % xxd -s -0x30 file

   Print 120 bytes as continuous hexdump with 20 octets per line.
   % xxd -l 120 -ps -c 20 xxd.1

   Hexdump the first 120 bytes of this man page with 12 octets per line.
   % xxd -l 120 -c 12 xxd.1
   0000000: 2e54 4820 5858 4420 3120 2241  .TH XXD 1 "A
   000000c: 7567 7573 7420 3139 3936 2220  ugust 1996"
   0000018: 224d 616e 7561 6c20 7061 6765  "Manual page
   0000024: 2066 6f72 2078 7864 220a 2e5c   for xxd"..\
   0000030: 220a 2e5c 2220 3231 7374 204d  "..\" 21st M
   000003c: 6179 2031 3939 360a 2e5c 2220  ay 1996..\"
   0000048: 4d61 6e20 7061 6765 2061 7574  Man page aut
   0000054: 686f 723a 0a2e 5c22 2020 2020  hor:..\"
   0000060: 546f 6e79 204e 7567 656e 7420  Tony Nugent
   000006c: 3c74 6f6e 7940 7363 746e 7567  <tony@sctnug

   Display just the date from the file xxd.1
   % xxd -s 0x36 -l 13 -c 13 xxd.1
   0000036: 3231 7374 204d 6179 2031 3939 36  21st May 1996

   Copy input_file to output_file and prepend 100 bytes of value 0x00.
   % xxd input_file | xxd -r -s 100 > output_file

   Patch the date in the file xxd.1
   % echo "0000037: 3574 68" | xxd -r - xxd.1
   % xxd -s 0x36 -l 13 -c 13 xxd.1
   0000036: 3235 7468 204d 6179 2031 3939 36  25th May 1996

   Create a 65537 byte file with all bytes 0x00, except for the  last  one
   which is 'A' (hex 0x41).
   % echo "010000: 41" | xxd -r > file

   Hexdump this file with autoskip.
   % xxd -a -c 12 file
   0000000: 0000 0000 0000 0000 0000 0000  ............
   000fffc: 0000 0000 40                   ....A

   Create  a  1  byte  file containing a single 'A' character.  The number
   after '-r -s' adds to the linenumbers found in the file; in effect, the
   leading bytes are suppressed.
   % echo "010000: 41" | xxd -r -s -0x10000 > file

   Use xxd as a filter within an editor such as vim(1) to hexdump a region
   marked between `a' and `z'.

   Use xxd as a filter within an editor such as vim(1) to recover a binary
   hexdump marked between `a' and `z'.
   :'a,'z!xxd -r

   Use xxd as a filter within an editor such as vim(1) to recover one line
   of a hexdump.  Move the cursor over the line and type:
   !!xxd -r

   Read single characters from a serial line
   % xxd -c1 < /dev/term/b &
   % stty < /dev/term/b -echo -opost -isig -icanon min 1
   % echo -n foo > /dev/term/b


   The following error values are returned:

   0      no errors encountered.

   -1     operation not supported ( xxd -r -i still impossible).

   1      error while parsing options.

   2      problems with input file.

   3      problems with output file.

   4,5    desired seek position is unreachable.


   uuencode(1), uudecode(1), patch(1)


   The tools weirdness matches its creators brain.  Use entirely  at  your
   own risk. Copy files. Trace it. Become a wizard.


   This manual page documents xxd version 1.7


   (c) 1990-1997 by Juergen Weigert

   Distribute freely and credit me,
   make money and share with me,
   lose money and don't ask me.

   Manual page started by Tony Nugent
   <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
   Small changes by Bram Moolenaar.  Edited by Juergen Weigert.


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