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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 speci-
     fied, in a user specified format.

     The options are as follows:

     -b          One-byte octal display.  Display the input offset in hexadecimal, followed by sixteen space-sepa-
                 rated, 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-sepa-
                 rated, 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-sep-
                 arated, 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 hexadecimal, followed by eight space-sepa-
                 rated, 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, 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 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 sep-
                 arated, 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, 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 whitespace.  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:

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

           ?   A byte count or field precision is required for each ''s'' conversion character (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 supported.

           ?   The single character escape sequences described in the C standard 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 hexadecimal respec-
                 tively.

     _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 char-
                 acter, 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 fol-
                 lowing, 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 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 incre-
     mented until the entire input block has been processed or there is not enough data remaining in the block to sat-
     isfy 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 conversion character with the same field width and pre-
     cision as the original conversion character or conversion string but with any "+", " ", "#" conversion flag char-
     acters 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.ker-
     nel.org/pub/linux/utils/util-linux-ng/.

BSD                             April 18, 1994                             BSD