1.\" $NetBSD: vis.1,v 1.19 2013/03/14 19:17:23 njoly Exp $ 2.\" 3.\" Copyright (c) 1989, 1991, 1993, 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)vis.1 8.4 (Berkeley) 4/19/94 31.\" 32.Dd February 19, 2013 33.Dt VIS 1 34.Os 35.Sh NAME 36.Nm vis 37.Nd display non-printable characters in a visual format 38.Sh SYNOPSIS 39.Nm 40.Op Fl bcfhlmnostw 41.Op Fl e Ar extra 42.Op Fl F Ar foldwidth 43.Op Ar file ... 44.Sh DESCRIPTION 45.Nm 46is a filter for converting non-printable characters 47into a visual representation. 48It differs from 49.Ql cat -v 50in that 51the form is unique and invertible. 52By default, all non-graphic 53characters except space, tab, and newline are encoded. 54A detailed description of the 55various visual formats is given in 56.Xr vis 3 . 57.Pp 58The options are as follows: 59.Bl -tag -width Ds 60.It Fl b 61Turns off prepending of backslash before up-arrow control sequences 62and meta characters, and disables the doubling of backslashes. 63This 64produces output which is neither invertible or precise, but does 65represent a minimum of change to the input. 66It is similar to 67.Dq Li cat -v . 68.Pq Dv VIS_NOSLASH 69.It Fl c 70Request a format which displays a small subset of the 71non-printable characters using C-style backslash sequences. 72.Pq Dv VIS_CSTYLE 73.It Fl e Ar extra 74Also encode characters in 75.Ar extra , 76per 77.Xr svis 3 . 78.It Fl F Ar foldwidth 79Causes 80.Nm 81to fold output lines to foldwidth columns (default 80), like 82.Xr fold 1 , 83except 84that a hidden newline sequence is used, (which is removed 85when inverting the file back to its original form with 86.Xr unvis 1 ) . 87If the last character in the encoded file does not end in a newline, 88a hidden newline sequence is appended to the output. 89This makes 90the output usable with various editors and other utilities which 91typically don't work with partial lines. 92.It Fl f 93Same as 94.Fl F . 95.It Fl h 96Encode using the URI encoding from RFC 1808. 97.Pq Dv VIS_HTTPSTYLE 98.It Fl l 99Mark newlines with the visible sequence 100.Ql \e$ , 101followed by the newline. 102.It Fl m 103Encode using the MIME Quoted-Printable encoding from RFC 2045. 104.Pq Dv VIS_MIMESTYLE 105.It Fl n 106Turns off any encoding, except for the fact that backslashes are 107still doubled and hidden newline sequences inserted if 108.Fl f 109or 110.Fl F 111is selected. 112When combined with the 113.Fl f 114flag, 115.Nm 116becomes like 117an invertible version of the 118.Xr fold 1 119utility. 120That is, the output can be unfolded by running the output through 121.Xr unvis 1 . 122.It Fl o 123Request a format which displays non-printable characters as 124an octal number, \eddd. 125.Pq Dv VIS_OCTAL 126.It Fl s 127Only characters considered unsafe to send to a terminal are encoded. 128This flag allows backspace, bell, and carriage return in addition 129to the default space, tab and newline. 130.Pq Dv VIS_SAFE 131.It Fl t 132Tabs are also encoded. 133.Pq Dv VIS_TAB 134.It Fl w 135White space (space-tab-newline) is also encoded. 136.Pq Dv VIS_WHITE 137.El 138.Sh MULTIBYTE CHARACTER SUPPORT 139.Nm 140supports multibyte character input. 141The encoding conversion is influenced by the setting of the 142.Ev LC_CTYPE 143environment variable which defines the set of characters that can be 144copied without encoding. 145.Pp 146When 8-bit data is present in the input, 147.Ev LC_CTYPE 148must be set to the correct locale or to the C locale. 149If the locales of the data and the conversion are mismatched, multibyte 150character recognition may fail and encoding will be performed byte-by-byte 151instead. 152.Sh ENVIRONMENT 153.Bl -tag -width ".Ev LC_CTYPE" 154.It Ev LC_CTYPE 155Specify the locale of the input data. 156Set to C if the input data locale is unknown. 157.El 158.Sh EXAMPLES 159Visualize characters encoding white spaces and tabs: 160.Bd -literal -offset indent 161$ echo -e "\\x10\\n\\t" | vis -w -t 162\\^P\\012\\011\\012 163.Ed 164.Pp 165Same as above but using `\\$' for newline followed by an actual newline: 166.Bd -literal -offset indent 167$ echo -e "\\x10\\n\\t" | vis -w -t -l 168\\^P\\$ 169\\011\\$ 170.Ed 171.Pp 172Visualize string using URI encoding: 173.Bd -literal -offset indent 174$ echo http://www.freebsd.org | vis -h 175http%3a%2f%2fwww.freebsd.org%0a 176.Ed 177.Sh SEE ALSO 178.Xr unvis 1 , 179.Xr svis 3 , 180.Xr vis 3 181.Sh HISTORY 182The 183.Nm 184command appears in 185.Bx 4.4 . 186Myltibyte character support was added in 187.Nx 7.0 188and 189.Fx 9.2 . 190