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HEXDUMP(1)                BSD General Commands Manual               HEXDUMP(1)

NAME
     hexdump - ascii, decimal, hexadecimal, octal dump

SYNOPSIS
     hexdump [-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 format.

     The options are as follows:

     -b          One-byte octal display.  Display the input offset in hexadecimal, fol-
                 lowed 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 hexadecimal,
                 followed by sixteen space-separated, three column, space-filled, charac-
                 ters 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, fol-
                 lowed by the same sixteen bytes in %_p format enclosed in ''|'' charac-
                 ters.

     -d          Two-byte decimal display.  Display the input offset in hexadecimal, fol-
                 lowed by eight space-separated, five column, zero-filled, two-byte units
                 of input data, in unsigned decimal, 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 hexadecimal, fol-
                 lowed by eight space-separated, six column, zero-filled, two byte quanti-
                 ties 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 number, 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 hexadecimal, per line.

     For each input file, hexdump sequentially copies the input to standard output, trans-
     forming 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 whitespace.  A for-
     mat 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:

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

           ?   A byte count or field precision is required for each ''s'' conversion char-
               acter (unlike the fprintf(3) default which prints the entire string if the
               precision is unspecified).

           ?   The conversion characters ''h'', ''l'', ''n'', ''p'' and ''q'' are not sup-
               ported.

           ?   The single character escape sequences described in the C standard are sup-
               ported:

                     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 hexadecimal respectively.

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

     _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 dis-
                 played 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 displayed 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 itera-
     tion 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 incre-
     mented 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 iteration.

     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 number 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 con-
     version character with the same field width and precision as the original conversion
     character or conversion string but with any "+", " ", "#" conversion flag characters
     removed, and referencing 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") compatible.

AVAILABILITY
     The hexdump command is part of the util-linux-ng package and is available from
     ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.

BSD                             April 18, 1994                             BSD

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