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XXD(1)                               General Commands Manual                               XXD(1)



NAME
       xxd - make a hexdump or do the reverse.

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

DESCRIPTION
       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  trans-
       mission  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 patching.

OPTIONS
       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 let-
       ter,  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,  hexa-
       decimal 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 combi-
              nations 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 std-
              out, 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  any-
              where.

       -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.

CAVEATS
       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 post-
       script) 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 interpreted.

       Note the difference between
       % xxd -i file
       and
       % 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.

EXAMPLES
       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
       2e54482058584420312022417567757374203139
       39362220224d616e75616c207061676520666f72
       20787864220a2e5c220a2e5c222032317374204d
       617920313939360a2e5c22204d616e2070616765
       20617574686f723a0a2e5c2220202020546f6e79
       204e7567656e74203c746f6e79407363746e7567

       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'.
       :'a,'z!xxd

       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

RETURN VALUES
       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.

SEE ALSO
       uuencode(1), uudecode(1), patch(1)

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

VERSION
       This manual page documents xxd version 1.7

AUTHOR
       (c) 1990-1997 by Juergen Weigert
       <jnweiger AT informatik.de>

       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 AT sctnugen.au> <T.Nugent AT sct.au>
       Small changes by Bram Moolenaar.  Edited by Juergen Weigert.

Manual page for xxd                        August 1996                                     XXD(1)

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