hexdump - ascii, decimal, hexadecimal, octal dump
hexdump [-bcCdovx] [-e format_string] [-f format_file] [-n
[-s skip] file ...
The hexdump utility is a filter which displays the specified
the standard input, if no files are specified, in a userspecified format.
The options are as follows:
-b One-byte octal display. Display the input offset in
followed by sixteen space-separated, three column,
bytes of input data, in octal, per line.
-c One-byte character display. Display the input offset in hexadecimal,
followed by sixteen space-separated, three
characters of input data per line.
-C Canonical hex+ASCII display. Display the input offset in hexadecimal,
followed by sixteen space-separated, two
bytes, followed by the same sixteen bytes
in %_p format
enclosed in ``|'' characters.
-d Two-byte decimal display. Display the input offset
followed by eight space-separated, five column,
two-byte units of input data, in unsigned decimal,
Specify a format string to be used for displaying
Specify a file that contains one or more newline
strings. Empty lines and lines whose first nonblank character
is a hash mark (`#') are ignored.
Interpret only length bytes of input.
-o Two-byte octal display. Display the input offset in
followed by eight space-separated, six column, zerofilled, two
byte quantities of input data, in octal, per line.
Skip offset bytes from the beginning of the input.
offset is interpreted as a decimal number. With a
leading 0x or
0X, offset is interpreted as a hexadecimal number,
with a leading 0, offset is interpreted as an octal
the character b, k, or m to offset causes it
to be interpreted
as a multiple of 512, 1024, or 1048576, respectively.
-v The -v option causes hexdump to display all input
the -v option, any number of groups of output lines,
be identical to the immediately preceding group of
(except for the input offsets), are replaced with a
of a single asterisk (`*').
-x Two-byte hexadecimal display. Display the input
offset in hexadecimal,
followed by eight, space separated, four
two-byte quantities of input data, in hexadecimal, per
For each input file, hexdump sequentially copies the input
output, transforming the data according to the format
by the -e and -f options, in the order that they were specified.
Formats [Toc] [Back]
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
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
(`/') must be placed after the iteration count and/or before
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
fprintf(3)), with the following exceptions:
+o An asterisk (*) may not be used as a field width
+o A byte count or field precision is required for
each `s' conversion
character (unlike the fprintf(3) default
the entire string if the precision is unspecified).
+o The conversion characters `h', `l', `n', `p', and
`q' are not
+o The single character escape sequences described in
the C stan- <
dard are supported: f
<alert character> m
<carriage return> e
<vertical tab> d
hexdump also supports the following additional conversion
_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
_A[dox] Identical to the _a conversion string except
that it is only
performed once, when all of the input data has
_c Output characters in the default character set.
characters are displayed in three character, zero-padded octal,
except for those representable by standard
(see above), which are displayed as two
_p Output characters in the default character set.
characters are displayed as a single dot `.'.
_u Output US ASCII characters, with the exception
characters are displayed using the following,
names. Characters greater than 0xff, hexadecimal, are displayed
as hexadecimal strings.
000 nul 001 soh 002 stx 003 etx 004 eot 005
006 ack 007 bel 008 bs 009 ht 00A lf 00B
00C ff 00D cr 00E so 00F si 010 dle 011
012 dc2 013 dc3 014 dc4 015 nak 016 syn 017
018 can 019 em 01A sub 01B esc 01C fs 01D
01E rs 01F us 0FF del
The default and supported byte counts for the conversion
%_c, %_p, %_u, %c One byte counts only.
%d, %i, %o, %u, %X, %x Four byte default, one, two,
four and eight
byte counts supported.
%E, %e, %f, %G, %g Eight byte default, four byte
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
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
unit both interprets some number of bytes and does not have
iteration count, have the iteration count incremented until
input block has been processed or there is not enough data
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
It is an error to specify a byte count as well as multiple
characters or strings unless all but one of the conversion
strings is _a or _A.
If, as a result of the specification of the -n option or
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
number of the zero bytes).
Further output by such format strings is replaced by an
of spaces. An equivalent number of spaces is defined as the
spaces output by an s conversion character with the same
field width and
precision as the original conversion character or conversion
with any `+', ` ', `#' conversion flag characters removed,
a NULL string.
If no format strings are specified, the default display is
specifying the -x option.
hexdump exits 0 on success and >0 if an error occurred.
Display the input in perusal format:
"%06.6_ao " 12/1 "%3_u "
"" "%_p "
Implement the -x option:
"%07.7_ax " 8/2 "%04x " "0
OpenBSD 3.6 April 18, 1994
[ Back ]