NAME

hexdump, hd - ASCII, decimal, hexadecimal, octal dump SYNOPSIS

hexdump [-bcCdovx [-e format_string [-f format_file [unrenderable node] [-s skip file ...

hd [-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 format.

The options are as follows

• b One-byte octal display. Display the input offsetin hexadecimal, followed by sixteen space-sepa-rated, three column, zero-filled, bytes of inputdata, in octal, per line.

• cOne-byte character display. Display the inputoffset in hexadecimal, followed by sixteenspace-separated, three column, space-filled,characters of input data per line.-CCanonical hex+ASCII display. Display the inputoffset in hexadecimal, followed by sixteenspace-separated, two column, hexadecimal bytes,followed by the same sixteen bytes in %_p formatenclosed in ``| characters.Calling the command hd implies this option.-dTwo-byte decimal display. Display the input off-set in hexadecimal, followed by eight space-sepa-rated, five column, zero-filled, two-byte unitsof input data, in unsigned decimal, per line.-e format_stringSpecify a format string to be used for displayingdata.-f format_fileSpecify a file that contains one or more newlineseparated format strings. Empty lines and lineswhose first non-blank character is a hash mark(#) are ignored.-n lengthInterpret only length bytes of input.-oTwo-byte octal display''. Display the input offsetin hexadecimal, followed by eight space-sepa-rated, six column, zero-filled, two byte quanti-ties of input data, in octal, per line.-s offsetSkip offset bytes from the beginning of theinput. By default, offset is interpreted as adecimal number. With a leading 0x or 0X, offsetis interpreted as a hexadecimal number, other-wise, with a leading 0, offset is interpreted asan octal number. Appending the character b, k,or m to offset causes it to be interpreted as amultiple 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 aster- isk.

• 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 specified.

Formats A format string contains any number of format units, sepa- rated 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 speci- fied 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 ( fprintf(3)), with the following excep- tions:

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 are supported:

NUL 0

Hexdump also supports the following additional conversion

strings

_a[dox Display the input offset, cumulative across inputfiles, of the next byte to be displayed. Theappended characters d, o, and x specify the dis-play base as decimal, octal or hexadecimalrespectively.

_A[doxIdentical to the _a conversion string except thatit is only performed once, when all of the inputdata has been processed._cOutput characters in the default character set.Nonprinting characters are displayed in threecharacter, zero-padded octal, except for thoserepresentable by standard escape notation (seeabove), which are displayed as two characterstrings._pOutput characters in the default character set.Nonprinting characters are displayed as a single``.''._uOutput US ASCII characters, with the exceptionthat control characters are displayed using thefollowing, lower-case, names. Characters greaterthan 0xff, hexadecimal, are displayed as hexadec-imal 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 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 specified by any for- mat string. Format strings interpreting less than an input block's worth of data, whose last format unit both inter- prets 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 mod- ifying 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 satis- fies a format string, the input block is zero-padded suffi- ciently 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.

DIAGNOSTICS EXAMPLES

Display the input in perusal format:

Implement the -x option:

SEE ALSO

gdb(1)

BSD April 18, 1994 1