HEXDUMP(1) BSD General Commands Manual HEXDUMP(1)
NAME
hexdump -- ASCII, decimal, hexadecimal, octal dump
SYNOPSIS
hexdump [-bcCdovx] [-e format_string] [-f format_file] [-n length] [-s skip] file ...
DESCRIPTION
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, spaceseparated,
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 for-mat format
mat 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, spaceseparated,
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-sepa-rated, space-separated,
rated, 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. By default, offset is interpreted as a dec-imal decimal
imal number. With a leading 0x or 0X, offset is interpreted as a hexadecimal number, other-wise, otherwise,
wise, with a leading 0, offset is interpreted as an octal number. Appending the character b,
k, or m to offset causes it to be interpreted as a multiple of 512, 1024, or 1048576, respec-tively. respectively.
tively.
-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 asterisk.
-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 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 speci-fied. specified.
fied.
Formats
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 itera-tion iteration
tion 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:
oo An asterisk (*) may not be used as a field width or precision.
oo 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).
oo The conversion characters ``h'', ``l'', ``n'', ``p'' and ``q'' are not supported.
oo The single character escape sequences described in the C standard are supported:
NUL \0
<alert character> \a
<backspace> \b
<form-feed> \f
<newline> \n
<carriage return> \r
<tab> \t
<vertical tab> \v
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 hexadeci-mal hexadecimal
mal 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 character, zero-padded octal, except for those representable by standard escape nota-tion notation
tion (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 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
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 and twelve 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 speci-fied specified
fied 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 avail-able available
able 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 a one-byte hexadecimal display.
DIAGNOSTICS
The hexdump utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
Note that the following format strings, used with -e, must be enclosed in single quotes.
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"
SEE ALSO
gdb(1), od(1)
BSD July 10, 2004 BSD
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