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.
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.
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.
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
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
-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.
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
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
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
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
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
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
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:
An asterisk (*) may not be used as a field width or
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).
The conversion characters h, l, n,
p, and q are not supported.
The single character escape sequences described in the C
standard are supported:
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 hexadecimal
Identical to the _a conversion string except that
it is only performed once, when all of the input data has been
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.
Output characters in the default character set.
Non-printing characters are displayed as a single '.'.
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
When put at the end of a format specifier, hexdump highlights the respective
string with the color specified. Conditions, if present, are evaluated prior
The full syntax of a color unit is as follows:
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.
One of the 8 basic shell colors.
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.
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
%_c, %_p, %_u, %c
One byte counts only.
%d, %i, %o, %u, %X,
Four byte default, one, two and four byte counts
%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
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
Display the input in perusal format:
"%06.6_ao " 12/1 "%3_u "
"\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
Implicit coloring can be disabled by an empty file
"%07.7_ax_L[cyan] " 8/2 " %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"
See terminal-colors.d(5) for more details about