hexdump [-bcdovx] [-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 for
mat.
The options are as follows:
-b One-byte octal display. Display the input offset in hexadeci
mal, 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 hex
adecimal, 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 hex
adecimal, followed by eight space-separated, five column, ze
ro-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 hexadeci
mal, 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. By de
fault, offset is interpreted as a decimal number. With a
leading 0x or 0X, offset is interpreted as a hexadecimal num
ber, otherwise, 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, respectively.
-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 separated, four column,
zero-filled, two-byte quantities of input data, in hexadeci
mal, per line.
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'' con
version 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 stan
dard are supported:
NUL \0
<alert character> \a
<backspace> \b
<form-feed> \f
<newline> \n
<carriage return> \r
<tab> \t
<vertical tab> \v
Hexdump also supports the 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 respectively.
_A[dox] Identical to the _a conversion string except that it is only
performed once, when all of the input data has been pro
cessed.
_c Output characters in the default character set. Nonprinting
characters are displayed in three character, zero-padded oc
tal, except for those representable by standard escape nota
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 ``.''.
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 byte counts sup
ported.
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 it
eration 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 be
ing reached, input data only partially satisfies a format string, the in
put 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 ref
erencing a NULL string.
If no format strings are specified, the default display is equivalent to
specifying the -x option.
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 "
BSD Experimental April 18, 1994 4
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