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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FORMATS | EXIT STATUS | CONFORMING TO | EXAMPLES | COLORS | REPORTING BUGS | AVAILABILITY |
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HEXDUMP(1) User Commands HEXDUMP(1)
hexdump - display file contents in hexadecimal, decimal, octal, or
ascii
hexdump [options] file ...
hd [options] file ...
The hexdump utility is a filter which displays the specified
files, or standard input if no files are specified, in a
user-specified format.
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.
-X, --one-byte-hex
One-byte hexadecimal display. Display the input offset in
hexadecimal, followed by sixteen space-separated, two-column,
zero-filled bytes of input data, in hexadecimal, 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.
-h, --help
Display help text and exit.
-V, --version
Display version 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.
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:
\0 NULL
\a alert character
\b backspace
\f form-feed
\n newline
\r carriage return
\t tab
\v vertical tab
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]
Almost 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.
00 nul 08 bs 10 dle 18 can 7F del
01 soh 09 ht 11 dc1 19 em
02 stx 0A lf 12 dc2 1A sub
03 etx 0B vt 13 dc3 1B esc
04 eot 0C ff 14 dc4 1C fs
05 enq 0D cr 15 nak 1D gs
06 ack 0E so 16 syn 1E rs
07 bel 0F si 17 etb 1F us
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).
hexdump exits 0 on success and > 0 if an error occurred.
The hexdump utility is expected to be IEEE Std 1003.2 ("POSIX.2")
compatible.
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"
The output colorization is implemented by terminal-colors.d(5)
functionality. Implicit coloring can be disabled by an empty file
/etc/terminal-colors.d/hexdump.disable
for the hexdump command or for all tools by
/etc/terminal-colors.d/disable
Since version 2.41, the $NO_COLOR environment variable is also
supported to disable output colorization unless explicitly enabled
by a command-line option.
The user-specific $XDG_CONFIG_HOME/terminal-colors.d or
$HOME/.config/terminal-colors.d overrides the global setting.
Note that the output colorization may be enabled by default, and
in this case terminal-colors.d directories do not have to exist
yet.
For bug reports, use the issue tracker
<https://github.com/util-linux/util-linux/issues>.
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
2025-08-11. (At that time, the date of the most recent commit that
was found in the repository was 2025-08-05.) 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 2.42-start-521-ec46 2025-08-09 HEXDUMP(1)
Pages that refer to this page: text2pcap(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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