NAME
   hexdump - ascii, decimal, hexadecimal, octal dump

SYNOPSIS
   [-bcCdovx] [-e format_string] [-f format_file] [-n length] [-s skip]
   file ...

DESCRIPTION
   The hexdump utility is a filter which displays the specified files, or
   the standard input, if no files are specified, in a user specified for-
   mat.

   The options are as follows:

   -b   One-byte octal display. Display the input offset in hexadec-
   imal, followed by sixteen space-separated, three column,
   zero-filled, bytes of input data, in octal, per line.

   -c   One-byte character display. Display the input offset in hex-
   adecimal, followed by sixteen space-separated, three column,
   space-filled, characters of input data per line.

   -C   Canonical hex+ASCII display. Display the input offset in
   hexadecimal, followed by sixteen space-separated, two column,
   hexadecimal bytes, followed by the same sixteen bytes in %_p
   format enclosed in ``|'' characters.

   -d   Two-byte decimal display. Display the input offset in hex-
   adecimal, followed by eight space-separated, five column,
   zero-filled, two-byte units of input data, in unsigned deci-
   mal, per line.

   -e format_string
   Specify a format string to be used for displaying data.

   -f format_file
   Specify a file that contains one or more newline separated
   format strings. Empty lines and lines whose first non-blank
   character is a hash mark (#) are ignored.

   -n length  Interpret only length bytes of input.

   -o   Two-byte octal display. Display the input offset in hexadec-
   imal, followed by eight space-separated, six column, zero-
   filled, two byte quantities of input data, in octal, per
   line.

   -s offset  Skip offset bytes from the beginning of the input. By
   default, offset is interpreted as a decimal number. With a
   leading 0x or 0X, offset is interpreted as a hexadecimal num-
   ber, otherwise, with a leading 0, offset is interpreted as an
   octal number. Appending the character b, k, or m to offset
   causes it to be interpreted as a multiple of 512, 1024, or
   1048576, respectively.

   -v   The -v option causes hexdump to display all input data.
   Without the -v option, any number of groups of output lines,
   which would be identical to the immediately preceding group
   of output lines (except for the input offsets), are replaced
   with a line comprised of a single asterisk.

   -x   Two-byte hexadecimal display. Display the input offset in
   hexadecimal, followed by eight, space separated, four column,
   zero-filled, two-byte quantities of input data, in hexadeci-
   mal, per line.

   For each input file, hexdump sequentially copies the input to standard
   output, transforming the data according to the format strings specified
   by the -e and -f options, in the order that they were specified.

 Formats
   A format string contains any number of format units, separated by whites-
   pace. A format unit contains up to three items: an iteration count, a
   byte count, and a format.

   The iteration count is an optional positive integer, which defaults to
   one. Each format is applied iteration count times.

   The byte count is an optional positive integer. If specified it defines
   the number of bytes to be interpreted by each iteration of the format.

   If an iteration count and/or a byte count is specified, a single slash
   must be placed after the iteration count and/or before the byte count to
   disambiguate them.  Any whitespace before or after the slash is ignored.

   The format is required and must be surrounded by double quote (" ")
   marks. It is interpreted as a fprintf-style format string (see
   fprintf(3)), with the following exceptions:

   o  An asterisk (*) may not be used as a field width or precision.

   o  A byte count or field precision is required for each ``s'' con-
     version character (unlike the fprintf(3) default which prints
     the entire string if the precision is unspecified).

   o  The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q''
     are not supported.

   o  The single character escape sequences described in the C stan-
     dard are supported:

     NUL   \0
     <alert character>  \a
     <backspace>  \b
     <form-feed>  \f
     <newline>   \n
     <carriage return>  \r
     <tab>   \t
     <vertical tab>  \v

   Hexdump also supports the following additional conversion strings:

   _a[dox]  Display the input offset, cumulative across input files, of
   the next byte to be displayed.  The appended characters d, o,
   and x specify the display base as decimal, octal or hexadeci-
   mal respectively.

   _A[dox]  Identical to the _a conversion string except that it is only
   performed once, when all of the input data has been pro-
   cessed.

   _c   Output characters in the default character set. Nonprinting
   characters are displayed in three character, zero-padded
   octal, except for those representable by standard escape
   notation (see above), which are displayed as two character
   strings.

   _p   Output characters in the default character set. Nonprinting
   characters are displayed as a single ``.''.

   _u   Output US ASCII characters, with the exception that control
   characters are displayed using the following, lower-case,
   names.  Characters greater than 0xff, hexadecimal, are dis-
   played as hexadecimal strings.

   000 nul 001 soh 002 stx 003 etx 004 eot 005 enq
   006 ack 007 bel 008 bs  009 ht  00A lf  00B vt
   00C ff  00D cr  00E so  00F si  010 dle 011 dc1
   012 dc2 013 dc3 014 dc4 015 nak 016 syn 017 etb
   018 can 019 em  01A sub 01B esc 01C fs  01D gs
   01E rs  01F us  0FF del

   The default and supported byte counts for the conversion characters are
   as follows:

   %_c, %_p, %_u, %c   One byte counts only.

   %u, %X, %x'      Four byte default, one, two and
      four byte counts supported.

   %G, %g' %f,    Eight byte default, four byte counts
      supported.

   The amount of data interpreted by each format string is the sum of the
   data required by each format unit, which is the iteration count times the
   byte count, or the iteration count times the number of bytes required by
   the format if the byte count is not specified.

   The input is manipulated in ``blocks'', where a block is defined as the
   largest amount of data specified by any format string. Format strings
   interpreting less than an input block's worth of data, whose last format
   unit both interprets some number of bytes and does not have a specified
   iteration count, have the iteration count incremented until the entire
   input block has been processed or there is not enough data remaining in
   the block to satisfy the format string.

   If, either as a result of user specification or hexdump modifying the
   iteration count as described above, an iteration count is greater than
   one, no trailing whitespace characters are output during the last itera-
   tion.

   It is an error to specify a byte count as well as multiple conversion
   characters or strings unless all but one of the conversion characters or
   strings is _a or _A.

   If, as a result of the specification of the -n option or end-of-file
   being reached, input data only partially satisfies a format string, the
   input block is zero-padded sufficiently to display all available data
   (i.e. any format units overlapping the end of data will display some num-
   ber of the zero bytes).

   Further output by such format strings is replaced by an equivalent number
   of spaces.  An equivalent number of spaces is defined as the number of
   spaces output by an s conversion character with the same field width and
   precision as the original conversion character or conversion string but
   with any ``+'', `` '', ``#'' conversion flag characters removed, and ref-
   erencing a NULL string.

   If no format strings are specified, the default display is equivalent to
   specifying the -x option.

   hexdump exits 0 on success and >0 if an error occurred.

EXAMPLES
   Display the input in perusal format:

   "%06.6_ao " 12/1 "%3_u "
   "\t\t" "%_p "
   "\n"

   Implement the -x option:

   "%07.7_Ax\n"
   "%07.7_ax " 8/2 "%04x " "\n"

STANDARDS
   The hexdump utility is expected to be IEEE Std 1003.2 (``POSIX.2'') com-
   patible.