Section: User Commands (1)
[-bcCdovx ] [-e format_string ] [-f format_file ] [-n length ] -words [-s skip ] file ...
The 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:
Calling the command hd implies this option.
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 iteration count and/or before the byte count to disambiguate them. Any whitespace before or after the slash is ignored.
<UL> <LI>An asterisk (*) may not be used as a field width or precision.</LI> <LI>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).</LI> <LI>The conversion characters ``%, ``h, ``l, ``n, ``p and ``q are not supported.</LI> <LI>The single character escape sequences described in the C standard are supported: <BLOCKQUOTE>:"NUL
\0 :"<alert character>
</BLOCKQUOTE> </LI> </UL>
utility also supports the following additional conversion 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 07F DEL
The default and supported byte counts for the conversion characters are as follows:
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 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.
Display the input in perusal format:
"%06.6_ao " 12/1 "%3_u " "\t\t" "%_p " "\n"</BLOCKQUOTE>
Implement the -x option:
"%07.7_Ax\n" "%07.7_ax " 8/2 "%04x " "\n"</BLOCKQUOTE>
Some examples for the -e option:
# hex bytes % echo hello | hexdump -v -e '/1 "%02X "' ; echo 68 65 6C 6C 6F 0A # same, with ASCII section % echo hello | hexdump -e '8/1 "%02X ""\t"" "' -e '8/1 "%c""\n"' 68 65 6C 6C 6F 0A hello # hex with preceding 'x' % echo hello | hexdump -v -e '"x" 1/1 "%02X" " "' ; echo x68 x65 x6C x6C x6F x0A # one hex byte per line % echo hello | hexdump -v -e '/1 "%02X\n"' 68 65 6C 6C 6F 0A # a table of byte#, hex, decimal, octal, ASCII % echo hello | hexdump -v -e '/1 "%_ad# "' -e '/1 "%02X hex"' -e '/1 " = %03i dec"' -e '/1 " = %03o oct"' -e '/1 " = _%c\_\n"' 0# 68 hex = 104 dec = 150 oct = _h_ 1# 65 hex = 101 dec = 145 oct = _e_ 2# 6C hex = 108 dec = 154 oct = _l_ 3# 6C hex = 108 dec = 154 oct = _l_ 4# 6F hex = 111 dec = 157 oct = _o_ 5# 0A hex = 010 dec = 012 oct = _ _ # byte# & ASCII with control chars % echo hello | hexdump -v -e '/1 "%_ad# "' -e '/1 " _%_u\_\n"' 0# _h_ 1# _e_ 2# _l_ 3# _l_ 4# _o_ 5# _lf_</BLOCKQUOTE>
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