hexdump(1) — Linux manual page

NAME | DESCRIPTION | OPTIONS | FORMATS | EXIT STATUS | CONFORMING TO | EXAMPLES | COLORS | REPORTING BUGS | AVAILABILITY

HEXDUMP(1)                    User Commands                   HEXDUMP(1)

NAME         top

       hexdump - display file contents in hexadecimal, decimal, octal,
       or ascii

       hexdump options file ...

       hd options file ...

DESCRIPTION         top

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

OPTIONS         top

       Below, the length and offset arguments may be followed by the
       multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on
       for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g.,
       "K" has the same meaning as "KiB"), or the suffixes KB (=1000),
       MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.

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

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

       -C, --canonical
           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. Invoking the program as hd
           implies this option.

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

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

       -f, --format-file 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.

       -L, --color[=when]
           Accept color units for the output. The optional argument when
           can be auto, never or always. If the when argument is
           omitted, it defaults to auto. The colors can be disabled; for
           the current built-in default see the --help output. See also
           the Colors subsection and the COLORS section below.

       -n, --length length
           Interpret only length bytes of input.

       -o, --two-bytes-octal
           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, --skip offset
           Skip offset bytes from the beginning of the input.

       -v, --no-squeezing
           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-bytes-hex
           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.

       -V, --version
           Display version information and exit.

       -h, --help
           Display help text and exit.

       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         top

       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:

       1.
           An asterisk (*) may not be used as a field width or
           precision.

       2.
           A byte count or field precision is required for each s
           conversion character (unlike the fprintf3 default which
           prints the entire string if the precision is unspecified).

       3.
           The conversion characters h, l, n, p, and q are not
           supported.

       4.
           The single character escape sequences described in the C
           standard are supported:

          ┌──────────────────┬────┐
          │                  │    │
          │NULL              │ \0 │
          ├──────────────────┼────┤
          │                  │    │
          │<alert character> │ \a │
          ├──────────────────┼────┤
          │                  │    │
          │<backspace>       │ \b │
          ├──────────────────┼────┤
          │                  │    │
          │<form-feed>       │ \f │
          ├──────────────────┼────┤
          │                  │    │
          │<newline>         │ \n │
          ├──────────────────┼────┤
          │                  │    │
          │<carriage return> │ \r │
          ├──────────────────┼────┤
          │                  │    │
          │<tab>             │ \t │
          ├──────────────────┼────┤
          │                  │    │
          │<vertical tab>    │ \v │
          └──────────────────┴────┘

   Conversion strings
       The hexdump utility 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.
           Non-printing 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.
           Non-printing 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 │         │         │         │
          └────────┴─────────┴─────────┴─────────┴─────────┴─────────┘

   Colors
       When put at the end of a format specifier, hexdump
       highlights the respective string with the color
       specified. Conditions, if present, are evaluated
       prior to highlighting.

       _L[color_unit_1,color_unit_2,...,color_unit_n]

       The full syntax of a color unit is as follows:

       [!]COLOR[:VALUE][@OFFSET_START[-END]]

       !
           Negate the condition. Please note that it only
           makes sense to negate a unit if both a
           value/string and an offset are specified. In that
           case the respective output string will be
           highlighted if and only if the value/string does
           not match the one at the offset.

       COLOR
           One of the 8 basic shell colors.

       VALUE
           A value to be matched specified in hexadecimal,
           or octal base, or as a string. Please note that
           the usual C escape sequences are not interpreted
           by hexdump inside the color_units.

       OFFSET
           An offset or an offset range at which to check
           for a match. Please note that lone OFFSET_START
           uses the same value as END offset.

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

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

       %d, %i, %o, %u, %X, %x
           Four byte default, one, two and four byte counts
           supported.

       %E, %e, %f, %G, %g
           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 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 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 very similar to the -x output format (the
       -x option causes more space to be used between format
       units than in the default output).

EXIT STATUS         top

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

CONFORMING TO         top

       The hexdump utility is expected to be IEEE Std 1003.2
       ("POSIX.2") compatible.

EXAMPLES         top

       Display the input in perusal format:

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

       Implement the -x option:

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

       MBR Boot Signature example: Highlight the addresses
       cyan and the bytes at offsets 510 and 511 green if
       their value is 0xAA55, red otherwise.

              "%07.7_Ax_L[cyan]\n"
              "%07.7_ax_L[cyan]  " 8/2 "   %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"

COLORS         top

       Implicit coloring can be disabled by an empty file
       /etc/terminal-colors.d/hexdump.disable.

       See terminal-colors.d(5) for more details about
       colorization configuration.

REPORTING BUGS         top

       For bug reports, use the issue tracker at
       https://github.com/karelzak/util-linux/issues.

AVAILABILITY         top

       The hexdump command is part of the util-linux package
       which can be downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.
       This page is part of the util-linux (a random
       collection of Linux utilities) project. Information
       about the project can be found at 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.
       If you have a bug report for this manual page, send
       it to util-linux@vger.kernel.org. This page was
       obtained from the project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩
       on 2021-08-27. (At that time, the date of the most
       recent commit that was found in the repository was
       2021-08-24.) If you discover any rendering problems
       in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the
       page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of
       the original manual page), send a mail to
       man-pages@man7.org

util-linux 2.37.85-637cc       2021-04-28                     HEXDUMP(1)