171 lines
5.1 KiB
Groff
171 lines
5.1 KiB
Groff
.\" $NetBSD: vis.1,v 1.20 2013/10/29 12:27:23 njoly Exp $
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.\"
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.\" Copyright (c) 1989, 1991, 1993, 1994
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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. 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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.\" @(#)vis.1 8.4 (Berkeley) 4/19/94
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.\"
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.Dd February 19, 2013
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.Dt VIS 1
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.Os
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.Sh NAME
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.Nm vis
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.Nd display non-printable characters in a visual format
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.Sh SYNOPSIS
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.Nm
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.Op Fl bcfhlmnostw
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.Op Fl e Ar extra
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.Op Fl F Ar foldwidth
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.Op Ar file ...
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.Sh DESCRIPTION
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.Nm
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is a filter for converting non-printable characters
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into a visual representation.
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It differs from
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.Ql cat -v
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in that
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the form is unique and invertible.
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By default, all non-graphic
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characters except space, tab, and newline are encoded.
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A detailed description of the
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various visual formats is given in
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.Xr vis 3 .
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl b
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Turns off prepending of backslash before up-arrow control sequences
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and meta characters, and disables the doubling of backslashes.
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This
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produces output which is neither invertible or precise, but does
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represent a minimum of change to the input.
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It is similar to
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.Dq Li cat -v .
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.Pq Dv VIS_NOSLASH
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.It Fl c
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Request a format which displays a small subset of the
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non-printable characters using C-style backslash sequences.
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.Pq Dv VIS_CSTYLE
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.It Fl e Ar extra
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Also encode characters in
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.Ar extra ,
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per
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.Xr svis 3 .
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.It Fl F Ar foldwidth
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Causes
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.Nm
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to fold output lines to foldwidth columns (default 80), like
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.Xr fold 1 ,
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except
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that a hidden newline sequence is used, (which is removed
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when inverting the file back to its original form with
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.Xr unvis 1 ) .
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If the last character in the encoded file does not end in a newline,
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a hidden newline sequence is appended to the output.
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This makes
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the output usable with various editors and other utilities which
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typically don't work with partial lines.
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.It Fl f
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Same as
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.Fl F .
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.It Fl h
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Encode using the URI encoding from RFC 1808.
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.Pq Dv VIS_HTTPSTYLE
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.It Fl l
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Mark newlines with the visible sequence
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.Ql \e$ ,
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followed by the newline.
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.It Fl m
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Encode using the MIME Quoted-Printable encoding from RFC 2045.
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.Pq Dv VIS_MIMESTYLE
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.It Fl n
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Turns off any encoding, except for the fact that backslashes are
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still doubled and hidden newline sequences inserted if
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.Fl f
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or
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.Fl F
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is selected.
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When combined with the
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.Fl f
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flag,
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.Nm
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becomes like
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an invertible version of the
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.Xr fold 1
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utility.
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That is, the output can be unfolded by running the output through
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.Xr unvis 1 .
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.It Fl o
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Request a format which displays non-printable characters as
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an octal number, \eddd.
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.Pq Dv VIS_OCTAL
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.It Fl s
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Only characters considered unsafe to send to a terminal are encoded.
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This flag allows backspace, bell, and carriage return in addition
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to the default space, tab and newline.
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.Pq Dv VIS_SAFE
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.It Fl t
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Tabs are also encoded.
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.Pq Dv VIS_TAB
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.It Fl w
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White space (space-tab-newline) is also encoded.
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.Pq Dv VIS_WHITE
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.El
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.Sh MULTIBYTE CHARACTER SUPPORT
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.Nm
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supports multibyte character input.
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The encoding conversion is influenced by the setting of the
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.Ev LC_CTYPE
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environment variable which defines the set of characters that can be
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copied without encoding.
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.Pp
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When 8-bit data is present in the input,
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.Ev LC_CTYPE
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must be set to the correct locale or to the C locale.
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If the locales of the data and the conversion are mismatched, multibyte
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character recognition may fail and encoding will be performed byte-by-byte
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instead.
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.Sh ENVIRONMENT
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.Bl -tag -width ".Ev LC_CTYPE"
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.It Ev LC_CTYPE
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Specify the locale of the input data.
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Set to C if the input data locale is unknown.
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.El
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.Sh SEE ALSO
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.Xr unvis 1 ,
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.Xr svis 3 ,
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.Xr vis 3
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.Sh HISTORY
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The
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.Nm
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command appears in
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.Bx 4.4 .
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Multibyte character support was added in
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.Nx 7.0
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and
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.Fx 9.2 .
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