325 lines
10 KiB
Groff
325 lines
10 KiB
Groff
.\" Copyright (c) 1989, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)hexdump.1 8.2 (Berkeley) 4/18/94
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.\"
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.TH HEXDUMP "1" "September 2011" "util-linux" "User Commands"
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.SH NAME
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hexdump \- display file contents in ascii, decimal, hexadecimal, or octal
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.SH SYNOPSIS
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.B hexdump
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[options] file [...]
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.SH DESCRIPTION
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The
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.B hexdump
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utility is a filter which displays the specified files, or
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standard input if no files are specified, in a user-specified
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format.
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.SH OPTIONS
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The \fIlength\fR and \fIoffset\fR arguments may be followed by the multiplicative
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suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB and YiB
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(the "iB" is optional, e.g. "K" has the same meaning as "KiB") or the suffixes
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KB=1000, MB=1000*1000, and so on for GB, PB, EB, ZB and YB.
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.TP
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.B \-b
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\fIOne-byte octal display\fR. Display the input offset in hexadecimal,
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followed by sixteen space-separated, three-column, zero-filled bytes of input
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data, in octal, per line.
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.TP
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.B \-c
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\fIOne-byte character display\fR. Display the input offset in hexadecimal,
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followed by sixteen space-separated, three-column, space-filled characters of
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input data per line.
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.TP
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.B \-C
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\fICanonical hex+ASCII display\fR. Display the input offset in hexadecimal,
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followed by sixteen space-separated, two-column, hexadecimal bytes, followed
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by the same sixteen bytes in
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.B %_p
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format enclosed in
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.RB ' | '
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characters.
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.TP
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.B \-d
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\fITwo-byte decimal display\fR. Display the input offset in hexadecimal,
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followed by eight space-separated, five-column, zero-filled, two-byte units
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of input data, in unsigned decimal, per line.
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.TP
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.BI \-e \ format_string
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Specify a format string to be used for displaying data.
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.TP
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.BI \-f \ format_file
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Specify a file that contains one or more newline separated format strings.
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Empty lines and lines whose first non-blank character is a hash mark (\&#)
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are ignored.
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.TP
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.BI \-n \ length
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Interpret only
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.I length
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bytes of input.
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.TP
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.B \-o
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\fITwo-byte octal display\fR. Display the input offset in hexadecimal,
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followed by eight space-separated, six-column, zero-filled, two-byte
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quantities of input data, in octal, per line.
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.TP
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.BI \-s \ offset
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Skip
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.I offset
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bytes from the beginning of the input.
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.TP
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.B \-v
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The
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.B \-v
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option causes
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.B hexdump
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to display all input data. Without the
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.B \-v
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option, any number of groups of output lines which would be identical to the
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immediately preceding group of output lines (except for the input offsets),
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are replaced with a line comprised of a single asterisk.
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.TP
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.B \-x
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\fITwo-byte hexadecimal display\fR. Display the input offset in hexadecimal,
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followed by eight space-separated, four-column, zero-filled, two-byte
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quantities of input data, in hexadecimal, per line.
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.PP
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For each input file,
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.B hexdump
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sequentially copies the input to standard output, transforming the data
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according to the format strings specified by the
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.B \-e
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and
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.B \-f
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options, in the order that they were specified.
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.SH FORMATS
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A format string contains any number of format units, separated by whitespace.
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A format unit contains up to three items: an iteration count, a byte count,
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and a format.
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.PP
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The iteration count is an optional positive integer, which defaults to one.
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Each format is applied iteration count times.
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.PP
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The byte count is an optional positive integer. If specified it defines the
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number of bytes to be interpreted by each iteration of the format.
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.PP
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If an iteration count and/or a byte count is specified, a single slash must
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be placed after the iteration count and/or before the byte count to
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disambiguate them. Any whitespace before or after the slash is ignored.
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.PP
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The format is required and must be surrounded by double quote (" ") marks.
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It is interpreted as a fprintf-style format string (see
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.BR fprintf (3),
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with the following exceptions:
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.TP
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1.
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An asterisk (*) may not be used as a field width or precision.
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.TP
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2.
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A byte count or field precision
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.I is
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required for each
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.B s
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conversion character (unlike the
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.BR fprintf (3)
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default which prints the entire string if the precision is unspecified).
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.TP
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3.
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The conversion characters
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.BR h , \ l , \ n , \ p ,
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.RB and \ q
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are not supported.
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.TP
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4.
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The single character escape sequences described in the C standard are
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supported:
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.PP
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.RS 13
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.PD 0
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.TP 21
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NULL
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\e0
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.TP
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<alert character>
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\ea
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.TP
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<backspace>
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\eb
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.TP
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<form-feed>
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\ef
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.TP
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<newline>
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\en
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.TP
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<carriage return>
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\er
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.TP
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<tab>
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\et
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.TP
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<vertical tab>
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\ev
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.PD
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.RE
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.PP
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.SS Conversion strings
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The
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.B hexdump
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utility also supports the following additional conversion strings.
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.TP
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.B \&_a[dox]
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Display the input offset, cumulative across input files, of the next byte to
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be displayed. The appended characters
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.BR d ,
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.BR o ,
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and
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.B x
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specify the display base as decimal, octal or hexadecimal respectively.
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.TP
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.B \&_A[dox]
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Identical to the
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.B \&_a
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conversion string except that it is only performed once, when all of the
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input data has been processed.
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.TP
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.B \&_c
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Output characters in the default character set. Nonprinting characters are
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displayed in three-character, zero-padded octal, except for those
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representable by standard escape notation (see above), which are displayed as
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two-character strings.
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.TP
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.B \&_p
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Output characters in the default character set. Nonprinting characters are
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displayed as a single
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.RB ' \&. '.
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.TP
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.B \&_u
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Output US ASCII characters, with the exception that control characters are
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displayed using the following, lower-case, names. Characters greater than
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0xff, hexadecimal, are displayed as hexadecimal strings.
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.PP
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.nf
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000 nul 001 soh 002 stx 003 etx 004 eot 005 enq
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006 ack 007 bel 008 bs 009 ht 00A lf 00B vt
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00C ff 00D cr 00E so 00F si 010 dle 011 dc1
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012 dc2 013 dc3 014 dc4 015 nak 016 syn 017 etb
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018 can 019 em 01A sub 01B esc 01C fs 01D gs
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01E rs 01F us 0FF del
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.nf
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.SS Counters
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The default and supported byte counts for the conversion characters
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are as follows:
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.TP
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.BR \&%_c , \ \&%_p , \ \&%_u , \ \&%c
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One byte counts only.
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.TP
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.BR \&%d , \ \&%i , \ \&%o , \ \&%u , \ \&%X , \ \&%x
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Four byte default, one, two and four byte counts supported.
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.TP
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.BR \&%E , \ \&%e , \ \&%f , \ \&%G , \ \&%g
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Eight byte default, four byte counts supported.
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.PP
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The amount of data interpreted by each format string is the sum of the data
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required by each format unit, which is the iteration count times the byte
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count, or the iteration count times the number of bytes required by the
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format if the byte count is not specified.
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.PP
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The input is manipulated in
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.IR blocks ,
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where a block is defined as the largest amount of data specified by any
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format string. Format strings interpreting less than an input block's worth
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of data, whose last format unit both interprets some number of bytes and does
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not have a specified iteration count, have the iteration count incremented
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until the entire input block has been processed or there is not enough data
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remaining in the block to satisfy the format string.
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.PP
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If, either as a result of user specification or
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.B hexdump
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modifying the iteration count as described above, an iteration count is
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greater than one, no trailing whitespace characters are output during the
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last iteration.
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.PP
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It is an error to specify a byte count as well as multiple conversion
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characters or strings unless all but one of the conversion characters or
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strings is
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.B \&_a
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or
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.BR \&_A .
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.PP
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If, as a result of the specification of the
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.B \-n
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option or end-of-file being reached, input data only partially satisfies a
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format string, the input block is zero-padded sufficiently to display all
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available data (i.e. any format units overlapping the end of data will
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display some number of the zero bytes).
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.PP
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Further output by such format strings is replaced by an equivalent number of
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spaces. An equivalent number of spaces is defined as the number of spaces
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output by an
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.B s
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conversion character with the same field width and precision as the original
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conversion character or conversion string but with any
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.RB ' \&+ ',
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\' \',
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.RB ' \&# '
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conversion flag characters removed, and referencing a NULL string.
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.PP
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If no format strings are specified, the default display is equivalent
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to specifying the
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.B \-x
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option.
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.SH "EXIT STATUS"
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.B hexdump
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exits 0 on success and >0 if an error occurred.
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.SH EXAMPLES
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Display the input in perusal format:
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.nf
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"%06.6_ao " 12/1 "%3_u "
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"\et\et" "%_p "
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"\en"
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.nf
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.PP
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Implement the \-x option:
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.nf
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"%07.7_Ax\en"
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"%07.7_ax " 8/2 "%04x " "\en"
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.nf
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.SH STANDARDS
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The
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.B hexdump
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utility is expected to be IEEE Std 1003.2 ("POSIX.2") compatible.
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.SH AVAILABILITY
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The hexdump command is part of the util-linux package and is available from
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.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
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Linux Kernel Archive
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.UE .
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