HD(C) UNIX System V
Name
hd - displays files in hexadecimal format
Syntax
hd [ -format [ -s offset ] [ -n count ] [ file ] ...
Description
The hd command displays the contents of files in
hexadecimal, octal, decimal, and character formats. Control
over the specification of ranges of characters is also
available. The default behavior is with the following flags
set: ``-abx -A''. This says that addresses (file offsets)
and bytes are printed in hexadecimal and that characters are
also printed. If no file argument is given, the standard
input is read.
Options include:
-s offset Specify the beginning offset in the file where
printing is to begin. If no `file' argument is
given, or if a seek fails because the input is a
pipe, `offset' bytes are read from the input and
discarded. Otherwise, a seek error will
terminate processing of the current file.
The offset may be given in decimal, hexadecimal
(preceded by `0x'), or octal (preceded by a
`0'). It is optionally followed by one of the
following multipliers: w, l, b, or k; for words
(2 bytes), long words (4 bytes), half kilobytes
(512 bytes), or kilobytes (1024 bytes),
respectively. Note that this is the one case
where ``b'' does not stand for bytes. Since
specifying a hexadecimal offset in blocks would
result in an ambiguous trailing `b', any offset
and multiplier may be separated by an asterisk
(*).
-n count Specify the number of bytes to process. The
count is in the same format as offset, above.
Format Flags
Format flags may specify addresses, characters, bytes, words
(2 bytes) or longs (4 bytes) to be printed in hex, decimal,
or octal. Two special formats may also be indicated: text
or ascii. Format and base specifiers may be freely combined
and repeated as desired in order to specify different bases
(hexadecimal, decimal or octal) for different output formats
(addresses, characters, etc.). All format flags appearing
in a single argument are applied as appropriate to all other
flags in that argument.
acbwlA
Output format specifiers for addresses, characters,
bytes, words, longs and ascii respectively. Only one
base specifier will be used for addresses. The address
will appear on the first line of output that begins
each new offset in the input.
The character format prints all printable characters
without change, special C escapes as defined in the
language, and the remaining values in the specified
base.
The ascii format prints all printable characters
without change, and all others as a period (.). This
format appears to the right of the first of other
specified output formats. A base specifier has no
meaning with the ascii format. If no other output
format (other than addresses) is given, bx is assumed.
If no base specifier is given, all of xdo are used.
xdo Output base specifiers for hexadecimal, decimal and
octal.
t Print a text file, each line preceded by the address in
the file. Normally, lines should be terminated by a \n
character; but long lines will be broken up. Control
characters in the range 0x00 to 0x1f are printed as
`^@' to `^_'. Bytes with the high bit set are preceded
by a tilde (~) and printed as if the high bit were not
set. The special characters (^, ~, \) are preceded by a
backslash (\) to escape their special meaning. As
special cases, these two values are represented
numerically as `\177' and `\377'. This flag will
override all output format specifiers except addresses.
If no output format is given, but a base specifier is
present, the output format is set to -acbwl. If no base
specifier is given, but an output format is present, the
base specifier is set to -xdo. If neither is present, the
format flag is set to -abx -A.
Value Added
hd is an extension of AT&T System V provided by the Santa
Cruz Operation.
(printed 8/28/89) HD(C)