hexdump(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FORMATS | EXIT STATUS | CONFORMING TO | EXAMPLES | COLORS | AVAILABILITY | COLOPHON

HEXDUMP(1)                    User Commands                   HEXDUMP(1)

NAME         top

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

SYNOPSIS         top

       hexdump [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 fprintf(3) 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\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.

AVAILABILITY         top

       The hexdump command is part of the util-linux package and is
       available from Linux Kernel Archive 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.

COLOPHON         top

       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
       2021-03-21.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-19.)  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                     April 2013                     HEXDUMP(1)