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    1 XXD(1)                      General Commands Manual                     XXD(1)
    2 
    3 
    4 
    5 NAME
    6        xxd - make a hexdump or do the reverse.
    7 
    8 SYNOPSIS
    9        xxd -h[elp]
   10        xxd [options] [infile [outfile]]
   11        xxd -r[evert] [options] [infile [outfile]]
   12 
   13 DESCRIPTION
   14        xxd  creates a hex dump of a given file or standard input.  It can also
   15        convert a hex dump back to its original binary form.  Like  uuencode(1)
   16        and  uudecode(1)  it allows the transmission of binary data in a `mail-
   17        safe' ASCII representation, but has the advantage of decoding to  stan‐
   18        dard output.  Moreover, it can be used to perform binary file patching.
   19 
   20 OPTIONS
   21        If  no infile is given, standard input is read.  If infile is specified
   22        as a `-' character, then input is taken from  standard  input.   If  no
   23        outfile is given (or a `-' character is in its place), results are sent
   24        to standard output.
   25 
   26        Note that a "lazy" parser is used which does not check  for  more  than
   27        the  first option letter, unless the option is followed by a parameter.
   28        Spaces between a single option letter and its parameter  are  optional.
   29        Parameters to options can be specified in decimal, hexadecimal or octal
   30        notation.  Thus -c8, -c 8, -c 010 and -cols 8 are all equivalent.
   31 
   32        -a | -autoskip
   33               Toggle autoskip: A single '*' replaces nul-lines.  Default off.
   34 
   35        -b | -bits
   36               Switch to bits (binary digits) dump, rather than hexdump.   This
   37               option  writes octets as eight digits "1"s and "0"s instead of a
   38               normal hexadecimal dump. Each line is preceded by a line  number
   39               in  hexadecimal and followed by an ascii (or ebcdic) representa‐
   40               tion. The command line switches -r, -p, -i do not work with this
   41               mode.
   42 
   43        -c cols | -cols cols
   44               Format  <cols> octets per line. Default 16 (-i: 12, -ps: 30, -b:
   45               6). Max 256.
   46 
   47        -C | -capitalize
   48               Capitalize variable names in C include file  style,  when  using
   49               -i.
   50 
   51        -E | -EBCDIC
   52               Change the character encoding in the righthand column from ASCII
   53               to EBCDIC.  This does not change the hexadecimal representation.
   54               The option is meaningless in combinations with -r, -p or -i.
   55 
   56        -e     Switch to little-endian hexdump.  This option treats byte groups
   57               as words in little-endian byte order.  The default grouping of 4
   58               bytes may be changed using -g.  This option only applies to hex‐
   59               dump, leaving the ASCII (or  EBCDIC)  representation  unchanged.
   60               The command line switches -r, -p, -i do not work with this mode.
   61 
   62        -g bytes | -groupsize bytes
   63               Separate  the  output of every <bytes> bytes (two hex characters
   64               or eight bit-digits each) by a whitespace.  Specify -g 0 to sup‐
   65               press grouping.  <Bytes> defaults to 2 in normal mode, 4 in lit‐
   66               tle-endian mode and 1 in bits mode.  Grouping does not apply  to
   67               postscript or include style.
   68 
   69        -h | -help
   70               Print  a summary of available commands and exit.  No hex dumping
   71               is performed.
   72 
   73        -i | -include
   74               Output in C include file style. A complete static array  defini‐
   75               tion  is  written (named after the input file), unless xxd reads
   76               from stdin.
   77 
   78        -l len | -len len
   79               Stop after writing <len> octets.
   80 
   81        -o offset
   82               Add <offset> to the displayed file position.
   83 
   84        -p | -ps | -postscript | -plain
   85               Output in postscript continuous hexdump  style.  Also  known  as
   86               plain hexdump style.
   87 
   88        -r | -revert
   89               Reverse  operation:  convert (or patch) hexdump into binary.  If
   90               not writing to stdout, xxd writes into its output  file  without
   91               truncating it. Use the combination -r -p to read plain hexadeci‐
   92               mal dumps without line number information and without a particu‐
   93               lar  column  layout.  Additional  Whitespace and line-breaks are
   94               allowed anywhere.
   95 
   96        -seek offset
   97               When used after -r: revert with <offset> added to file positions
   98               found in hexdump.
   99 
  100        -s [+][-]seek
  101               Start at <seek> bytes abs. (or rel.) infile offset.  + indicates
  102               that the seek is relative to the  current  stdin  file  position
  103               (meaningless when not reading from stdin).  - indicates that the
  104               seek should be that many characters from the end  of  the  input
  105               (or if combined with +: before the current stdin file position).
  106               Without -s option, xxd starts at the current file position.
  107 
  108        -u     Use upper case hex letters. Default is lower case.
  109 
  110        -v | -version
  111               Show version string.
  112 
  113 CAVEATS
  114        xxd -r has some builtin magic while evaluating line number information.
  115        If  the  output  file is seekable, then the linenumbers at the start of
  116        each hexdump line may be out of order, lines may be missing,  or  over‐
  117        lapping.  In these cases xxd will lseek(2) to the next position. If the
  118        output file is not seekable, only  gaps  are  allowed,  which  will  be
  119        filled by null-bytes.
  120 
  121        xxd -r never generates parse errors. Garbage is silently skipped.
  122 
  123        When  editing hexdumps, please note that xxd -r skips everything on the
  124        input line after reading enough columns of hexadecimal data (see option
  125        -c).  This  also means, that changes to the printable ascii (or ebcdic)
  126        columns are always ignored. Reverting a  plain  (or  postscript)  style
  127        hexdump  with  xxd  -r -p does not depend on the correct number of col‐
  128        umns. Here anything that looks like a  pair  of  hex-digits  is  inter‐
  129        preted.
  130 
  131        Note the difference between
  132        % xxd -i file
  133        and
  134        % xxd -i < file
  135 
  136        xxd  -s +seek may be different from xxd -s seek, as lseek(2) is used to
  137        "rewind" input.  A '+' makes a difference if the input source is stdin,
  138        and  if  stdin's  file  position is not at the start of the file by the
  139        time xxd is started and given its input.  The  following  examples  may
  140        help to clarify (or further confuse!)...
  141 
  142        Rewind  stdin before reading; needed because the `cat' has already read
  143        to the end of stdin.
  144        % sh -c "cat > plain_copy; xxd -s 0 > hex_copy" < file
  145 
  146        Hexdump from file position 0x480 (=1024+128)  onwards.   The  `+'  sign
  147        means "relative to the current position", thus the `128' adds to the 1k
  148        where dd left off.
  149        % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +128 >  hex_snippet"
  150        < file
  151 
  152        Hexdump from file position 0x100 ( = 1024-768) on.
  153        % sh -c "dd of=plain_snippet bs=1k count=1; xxd -s +-768 > hex_snippet"
  154        < file
  155 
  156        However, this is a rare situation and the use of `+' is rarely  needed.
  157        The  author  prefers  to  monitor  the  effect of xxd with strace(1) or
  158        truss(1), whenever -s is used.
  159 
  160 EXAMPLES
  161        Print everything but the first three lines (hex 0x30 bytes) of file.
  162        % xxd -s 0x30 file
  163 
  164        Print 3 lines (hex 0x30 bytes) from the end of file.
  165        % xxd -s -0x30 file
  166 
  167        Print 120 bytes as continuous hexdump with 20 octets per line.
  168        % xxd -l 120 -ps -c 20 xxd.1
  169        2e54482058584420312022417567757374203139
  170        39362220224d616e75616c207061676520666f72
  171        20787864220a2e5c220a2e5c222032317374204d
  172        617920313939360a2e5c22204d616e2070616765
  173        20617574686f723a0a2e5c2220202020546f6e79
  174        204e7567656e74203c746f6e79407363746e7567
  175 
  176        Hexdump the first 120 bytes of this man page with 12 octets per line.
  177        % xxd -l 120 -c 12 xxd.1
  178        0000000: 2e54 4820 5858 4420 3120 2241  .TH XXD 1 "A
  179        000000c: 7567 7573 7420 3139 3936 2220  ugust 1996"
  180        0000018: 224d 616e 7561 6c20 7061 6765  "Manual page
  181        0000024: 2066 6f72 2078 7864 220a 2e5c   for xxd"..\
  182        0000030: 220a 2e5c 2220 3231 7374 204d  "..\" 21st M
  183        000003c: 6179 2031 3939 360a 2e5c 2220  ay 1996..\"
  184        0000048: 4d61 6e20 7061 6765 2061 7574  Man page aut
  185        0000054: 686f 723a 0a2e 5c22 2020 2020  hor:..\"
  186        0000060: 546f 6e79 204e 7567 656e 7420  Tony Nugent
  187        000006c: 3c74 6f6e 7940 7363 746e 7567  <tony@sctnug
  188 
  189        Display just the date from the file xxd.1
  190        % xxd -s 0x36 -l 13 -c 13 xxd.1
  191        0000036: 3231 7374 204d 6179 2031 3939 36  21st May 1996
  192 
  193        Copy input_file to output_file and prepend 100 bytes of value 0x00.
  194        % xxd input_file | xxd -r -s 100 > output_file
  195 
  196        Patch the date in the file xxd.1
  197        % echo "0000037: 3574 68" | xxd -r - xxd.1
  198        % xxd -s 0x36 -l 13 -c 13 xxd.1
  199        0000036: 3235 7468 204d 6179 2031 3939 36  25th May 1996
  200 
  201        Create a 65537 byte file with all bytes 0x00, except for the  last  one
  202        which is 'A' (hex 0x41).
  203        % echo "010000: 41" | xxd -r > file
  204 
  205        Hexdump this file with autoskip.
  206        % xxd -a -c 12 file
  207        0000000: 0000 0000 0000 0000 0000 0000  ............
  208        *
  209        000fffc: 0000 0000 40                   ....A
  210 
  211        Create  a  1  byte  file containing a single 'A' character.  The number
  212        after '-r -s' adds to the linenumbers found in the file; in effect, the
  213        leading bytes are suppressed.
  214        % echo "010000: 41" | xxd -r -s -0x10000 > file
  215 
  216        Use xxd as a filter within an editor such as vim(1) to hexdump a region
  217        marked between `a' and `z'.
  218        :'a,'z!xxd
  219 
  220        Use xxd as a filter within an editor such as vim(1) to recover a binary
  221        hexdump marked between `a' and `z'.
  222        :'a,'z!xxd -r
  223 
  224        Use xxd as a filter within an editor such as vim(1) to recover one line
  225        of a hexdump.  Move the cursor over the line and type:
  226        !!xxd -r
  227 
  228        Read single characters from a serial line
  229        % xxd -c1 < /dev/term/b &
  230        % stty < /dev/term/b -echo -opost -isig -icanon min 1
  231        % echo -n foo > /dev/term/b
  232 
  233 RETURN VALUES
  234        The following error values are returned:
  235 
  236        0      no errors encountered.
  237 
  238        -1     operation not supported ( xxd -r -i still impossible).
  239 
  240        1      error while parsing options.
  241 
  242        2      problems with input file.
  243 
  244        3      problems with output file.
  245 
  246        4,5    desired seek position is unreachable.
  247 
  248 SEE ALSO
  249        uuencode(1), uudecode(1), patch(1)
  250 
  251 WARNINGS
  252        The tools weirdness matches its creators brain.  Use entirely  at  your
  253        own risk. Copy files. Trace it. Become a wizard.
  254 
  255 VERSION
  256        This manual page documents xxd version 1.7
  257 
  258 AUTHOR
  259        (c) 1990-1997 by Juergen Weigert
  260        <jnweiger@informatik.uni-erlangen.de>
  261 
  262        Distribute freely and credit me,
  263        make money and share with me,
  264        lose money and don't ask me.
  265 
  266        Manual page started by Tony Nugent
  267        <tony@sctnugen.ppp.gu.edu.au> <T.Nugent@sct.gu.edu.au>
  268        Small changes by Bram Moolenaar.  Edited by Juergen Weigert.
  269 
  270 Manual page for xxd               August 1996                           XXD(1)