HEXDUMP(1) User Commands HEXDUMP(1)
NAME
hexdump - display file contents in ascii, decimal, hexadecimal, or octal
SYNOPSIS
hexdump [options] file [...]
DESCRIPTION
The hexdump utility is a filter which displays the specified files, or standard input if no files are speci‐
fied, in a user-specified format.
OPTIONS
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 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 character display. Display the input offset in hexadecimal, followed by sixteen space-sepa‐
rated, three-column, space-filled characters of input data per line.
-C Canonical hex+ASCII display. Display the input offset in hexadecimal, followed by sixteen space-sepa‐
rated, two-column, hexadecimal bytes, followed by the same sixteen bytes in %_p format enclosed in '|'
characters.
-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.
-e format_string
Specify a format string to be used for displaying data.
-f format_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.
-n length
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.
-s offset
Skip offset bytes from the beginning of the input.
-v 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-byte hexadecimal display. Display the input offset in hexadecimal, followed by eight space-sepa‐
rated, four-column, zero-filled, two-byte quantities of input data, in hexadecimal, per line.
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.
FORMATS
A format string contains any number of format units, separated by whitespace. A format unit contains up to
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. Nonprinting characters are displayed in three-charac‐
ter, 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. Nonprinting characters are displayed as a single '.'.
_u Output US ASCII characters, with the exception that control characters are displayed using the follow‐
ing, 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
Counters
The default and supported byte counts for the conversion characters are as follows:
%_c, %_p, %_u, %c
One byte counts only.
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 equivalent to specifying the -x option.
EXIT STATUS
hexdump exits 0 on success and >0 if an error occurred.
EXAMPLES
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"
STANDARDS
The hexdump utility is expected to be IEEE Std 1003.2 ("POSIX.2") compatible.
AVAILABILITY
The hexdump command is part of the util-linux package and is available from Linux Kernel Archive ⟨ftp://
ftp.kernel.org/pub/linux/utils/util-linux/⟩.
util-linux September 2011 HEXDUMP(1)
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