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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FORMATS | EXIT STATUS | CONFORMING TO | EXAMPLES | COLORS | AVAILABILITY | COLOPHON |
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HEXDUMP(1) User Commands HEXDUMP(1)
hexdump - display file contents in hexadecimal, decimal, octal,
or ascii
hexdump [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.
-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.
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).
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\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"
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.
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/⟩.
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
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) 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)
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