HEXDUMP(1) General Commands Manual HEXDUMP(1)
hexdump – ASCII, decimal, hexadecimal, octal dump
hexdump [-bcCdovx] [-e format_string] [-f format_file] [-n length]
[-s skip] file ...
The hexdump utility is a filter which displays the specified files, or the
standard input, if no files are specified, in a user specified format.
The options are as follows:
-b 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 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.
-c 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.
-d 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.
Specify a format string to be used for displaying data.
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.
Interpret only length bytes of input.
-o 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.
Skip offset bytes from the beginning of the input. By default,
offset is interpreted as a decimal number. With a leading 0x or
0X, offset is interpreted as a hexadecimal number, otherwise, with
a leading 0, offset is interpreted as an octal number. Appending
the character b, k, m, or g to offset causes it to be interpreted
as a multiple of 512, 1024, 1048576, or 1073741824, respectively.
-v Cause 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
-x 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
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:
• An asterisk (*) may not be used as a field width or precision.
• 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).
• The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q''
are not supported.
• The single character escape sequences described in the C standard
<alert character> \a
<carriage return> \r
<vertical tab> \v
The hexdump utility also supports the following additional conversion
Cm _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
_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. Nonprinting
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 ASCII character set. Non-ASCII
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 NUL001 SOH002 STX003 ETX004 EOT005 ENQ
006 ACK007 BEL008 BS009 HT00A LF00B VT
00C FF00D CR00E SO00F SI010 DLE011 DC1
012 DC2013 DC3014 DC4015 NAK016 SYN017 ETB
018 CAN019 EM01A SUB01B ESC01C FS01D GS
01E RS01F US0FF DEL
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, %x Four byte default, one, two and four byte
%E, %e, %f, %G, %g Eight byte default, four and twelve 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 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
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 a one-byte
The hexdump utility exits 0 on success, and >0 if an error occurs.
Note that the following format strings, used with -e, must be enclosed in
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"
macOS 12.1 July 10, 2004 macOS 12.1