2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
354 lines
8 KiB
Groff
354 lines
8 KiB
Groff
.\" $NetBSD: vis.3,v 1.23 2009/02/10 23:06:31 christos Exp $
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.\"
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.\" Copyright (c) 1989, 1991, 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. 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.3 8.1 (Berkeley) 6/9/93
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.\"
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.Dd February 10, 2009
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.Dt VIS 3
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.Os
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.Sh NAME
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.Nm vis ,
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.Nm strvis ,
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.Nm strvisx ,
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.Nm svis ,
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.Nm strsvis ,
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.Nm strsvisx
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.Nd visually encode characters
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In vis.h
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.Ft char *
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.Fn vis "char *dst" "int c" "int flag" "int nextc"
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.Ft int
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.Fn strvis "char *dst" "const char *src" "int flag"
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.Ft int
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.Fn strvisx "char *dst" "const char *src" "size_t len" "int flag"
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.Ft char *
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.Fn svis "char *dst" "int c" "int flag" "int nextc" "const char *extra"
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.Ft int
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.Fn strsvis "char *dst" "const char *src" "int flag" "const char *extra"
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.Ft int
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.Fn strsvisx "char *dst" "const char *src" "size_t len" "int flag" "const char *extra"
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.Sh DESCRIPTION
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The
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.Fn vis
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function
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copies into
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.Fa dst
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a string which represents the character
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.Fa c .
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If
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.Fa c
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needs no encoding, it is copied in unaltered.
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The string is null terminated, and a pointer to the end of the string is
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returned.
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The maximum length of any encoding is four
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characters (not including the trailing
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.Dv NUL ) ;
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thus, when
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encoding a set of characters into a buffer, the size of the buffer should
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be four times the number of characters encoded, plus one for the trailing
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.Dv NUL .
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The flag parameter is used for altering the default range of
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characters considered for encoding and for altering the visual
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representation.
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The additional character,
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.Fa nextc ,
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is only used when selecting the
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.Dv VIS_CSTYLE
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encoding format (explained below).
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.Pp
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The
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.Fn strvis
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and
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.Fn strvisx
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functions copy into
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.Fa dst
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a visual representation of
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the string
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.Fa src .
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The
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.Fn strvis
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function encodes characters from
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.Fa src
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up to the
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first
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.Dv NUL .
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The
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.Fn strvisx
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function encodes exactly
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.Fa len
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characters from
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.Fa src
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(this
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is useful for encoding a block of data that may contain
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.Dv NUL Ns 's ) .
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Both forms
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.Dv NUL
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terminate
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.Fa dst .
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The size of
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.Fa dst
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must be four times the number
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of characters encoded from
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.Fa src
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(plus one for the
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.Dv NUL ) .
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Both
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forms return the number of characters in dst (not including
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the trailing
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.Dv NUL ) .
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.Pp
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The functions
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.Fn svis ,
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.Fn strsvis ,
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and
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.Fn strsvisx
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correspond to
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.Fn vis ,
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.Fn strvis ,
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and
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.Fn strvisx
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but have an additional argument
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.Fa extra ,
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pointing to a
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.Dv NUL
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terminated list of characters.
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These characters will be copied encoded or backslash-escaped into
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.Fa dst .
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These functions are useful e.g. to remove the special meaning
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of certain characters to shells.
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.Pp
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The encoding is a unique, invertible representation composed entirely of
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graphic characters; it can be decoded back into the original form using
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the
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.Xr unvis 3
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or
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.Xr strunvis 3
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functions.
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.Pp
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There are two parameters that can be controlled: the range of
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characters that are encoded (applies only to
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.Fn vis ,
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.Fn strvis ,
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and
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.Fn strvisx ) ,
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and the type of representation used.
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By default, all non-graphic characters,
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except space, tab, and newline are encoded.
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(See
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.Xr isgraph 3 . )
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The following flags
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alter this:
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.Bl -tag -width VIS_WHITEX
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.It Dv VIS_SP
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Also encode space.
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.It Dv VIS_TAB
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Also encode tab.
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.It Dv VIS_NL
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Also encode newline.
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.It Dv VIS_WHITE
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Synonym for
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.Dv VIS_SP
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\&|
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.Dv VIS_TAB
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\&|
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.Dv VIS_NL .
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.It Dv VIS_SAFE
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Only encode "unsafe" characters.
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Unsafe means control characters which may cause common terminals to perform
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unexpected functions.
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Currently this form allows space, tab, newline, backspace, bell, and
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return - in addition to all graphic characters - unencoded.
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.El
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.Pp
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(The above flags have no effect for
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.Fn svis ,
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.Fn strsvis ,
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and
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.Fn strsvisx .
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When using these functions, place all graphic characters to be
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encoded in an array pointed to by
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.Fa extra .
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In general, the backslash character should be included in this array, see the
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warning on the use of the
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.Dv VIS_NOSLASH
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flag below).
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.Pp
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There are four forms of encoding.
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All forms use the backslash character
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.Ql \e
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to introduce a special
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sequence; two backslashes are used to represent a real backslash,
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except
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.Dv VIS_HTTPSTYLE
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that uses
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.Ql % ,
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or
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.Dv VIS_MIMESTYLE
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that uses
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.Ql = .
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These are the visual formats:
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.Bl -tag -width VIS_CSTYLE
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.It (default)
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Use an
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.Ql M
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to represent meta characters (characters with the 8th
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bit set), and use caret
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.Ql ^
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to represent control characters see
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.Pf ( Xr iscntrl 3 ) .
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The following formats are used:
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.Bl -tag -width xxxxx
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.It Dv \e^C
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Represents the control character
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.Ql C .
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Spans characters
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.Ql \e000
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through
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.Ql \e037 ,
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and
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.Ql \e177
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(as
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.Ql \e^? ) .
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.It Dv \eM-C
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Represents character
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.Ql C
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with the 8th bit set.
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Spans characters
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.Ql \e241
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through
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.Ql \e376 .
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.It Dv \eM^C
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Represents control character
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.Ql C
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with the 8th bit set.
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Spans characters
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.Ql \e200
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through
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.Ql \e237 ,
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and
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.Ql \e377
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(as
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.Ql \eM^? ) .
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.It Dv \e040
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Represents
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.Tn ASCII
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space.
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.It Dv \e240
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Represents Meta-space.
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.El
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.Pp
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.It Dv VIS_CSTYLE
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Use C-style backslash sequences to represent standard non-printable
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characters.
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The following sequences are used to represent the indicated characters:
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.Bd -unfilled -offset indent
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.Li \ea Tn - BEL No (007)
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.Li \eb Tn - BS No (010)
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.Li \ef Tn - NP No (014)
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.Li \en Tn - NL No (012)
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.Li \er Tn - CR No (015)
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.Li \es Tn - SP No (040)
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.Li \et Tn - HT No (011)
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.Li \ev Tn - VT No (013)
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.Li \e0 Tn - NUL No (000)
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.Ed
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.Pp
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When using this format, the nextc parameter is looked at to determine
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if a
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.Dv NUL
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character can be encoded as
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.Ql \e0
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instead of
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.Ql \e000 .
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If
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.Fa nextc
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is an octal digit, the latter representation is used to
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avoid ambiguity.
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.It Dv VIS_OCTAL
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Use a three digit octal sequence.
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The form is
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.Ql \eddd
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where
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.Em d
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represents an octal digit.
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.It Dv VIS_HTTPSTYLE
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Use URI encoding as described in RFC 1738.
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The form is
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.Ql %xx
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where
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.Em x
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represents a lower case hexadecimal digit.
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.It Dv VIS_MIMESTYLE
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Use MIME Quoted-Printable encoding as described in RFC 2045, only don't
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break lines and don't handle CRLF.
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The form is:
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.Ql %XX
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where
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.Em X
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represents an upper case hexadecimal digit.
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.El
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.Pp
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There is one additional flag,
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.Dv VIS_NOSLASH ,
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which inhibits the
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doubling of backslashes and the backslash before the default
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format (that is, control characters are represented by
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.Ql ^C
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and
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meta characters as
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.Ql M-C ) .
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With this flag set, the encoding is
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ambiguous and non-invertible.
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.Sh SEE ALSO
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.Xr unvis 1 ,
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.Xr vis 1 ,
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.Xr unvis 3
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.Rs
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.%A T. Berners-Lee
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.%T Uniform Resource Locators (URL)
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.%O RFC1738
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.Re
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.Sh HISTORY
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The
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.Fa vis ,
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.Fa strvis ,
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and
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.Fa strvisx
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functions first appeared in
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.Bx 4.4 .
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The
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.Fa svis ,
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.Fa strsvis ,
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and
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.Fa strsvisx
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functions appeared in
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.Nx 1.5 .
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