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-octalOne-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-charOne-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, --canonicalCanonical 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.
-d, --two-bytes-decimalTwo-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.
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-octalTwo-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
-s, --skip offset
Skip offset bytes from the beginning of the input.
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-hexTwo-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.
Display version information and exit.
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
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
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
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:
<alert character> \a
<carriage return> \r
<vertical tab> \v
The hexdump utility also supports the following additional conversion
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
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
_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
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.
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
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
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
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).
Display the input in perusal format:
"%06.6_ao " 12/1 "%3_u "
"\t\t" "%_p "
Implement the -x option:
"%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] " 8/2 " %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"
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
firstname.lastname@example.org. This page was obtained from the
project's upstream Git repository
2017-03-13. If you discover any rendering problems in this HTML ver‐
sion 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 man‐
ual page), send a mail to email@example.com
util-linux April 2013 HEXDUMP(1)