1.\" Copyright (c) 1989, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)vis.1 8.4 (Berkeley) 4/19/94 29.\" $FreeBSD: src/usr.bin/vis/vis.1,v 1.6.2.2 2002/06/21 15:30:07 charnier Exp $ 30.\" $DragonFly: src/usr.bin/vis/vis.1,v 1.2 2003/06/17 04:29:33 dillon Exp $ 31.\" 32.Dd April 19, 1994 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 cbflnostw 41.Op Fl F Ar foldwidth 42.Op Ar 43.Sh DESCRIPTION 44The 45.Nm 46utility is a filter for converting non-printable characters 47into a visual representation. It differs from 48.Ql cat -v 49in that 50the form is unique and invertible. By default, all non-graphic 51characters except space, tab, and newline are encoded. 52A detailed description of the 53various visual formats is given in 54.Xr vis 3 . 55.Pp 56The options are as follows: 57.Bl -tag -width Ds 58.It Fl b 59Turns off prepending of backslash before up-arrow control sequences 60and meta characters, and disables the doubling of backslashes. This 61produces output which is neither invertible or precise, but does 62represent a minimum of change to the input. It is similar to 63.Dq Li cat -v . 64.It Fl c 65Request a format which displays a small subset of the 66non-printable characters using C-style backslash sequences. 67.It Fl F 68Causes 69.Nm 70to fold output lines to foldwidth columns (default 80), like 71.Xr fold 1 , 72except 73that a hidden newline sequence is used, (which is removed 74when inverting the file back to its original form with 75.Xr unvis 1 ) . 76If the last character in the encoded file does not end in a newline, 77a hidden newline sequence is appended to the output. 78This makes 79the output usable with various editors and other utilities which 80typically don't work with partial lines. 81.It Fl f 82Same as 83.Fl F . 84.It Fl l 85Mark newlines with the visible sequence 86.Ql \e$ , 87followed by the newline. 88.It Fl n 89Turns off any encoding, except for the fact that backslashes are 90still doubled and hidden newline sequences inserted if 91.Fl f 92or 93.Fl F 94is selected. When combined with the 95.Fl f 96flag, 97.Nm 98becomes like 99an invertible version of the 100.Xr fold 1 101utility. That is, the output 102can be unfolded by running the output through 103.Xr unvis 1 . 104.It Fl o 105Request a format which displays non-printable characters as 106an octal number, \eddd. 107.It Fl s 108Only characters considered unsafe to send to a terminal are encoded. 109This flag allows backspace, bell, and carriage return in addition 110to the default space, tab and newline. 111.It Fl t 112Tabs are also encoded. 113.It Fl w 114White space (space-tab-newline) is also encoded. 115.El 116.Sh SEE ALSO 117.Xr unvis 1 , 118.Xr vis 3 119.Sh HISTORY 120The 121.Nm 122command appeared in 123.Bx 4.4 . 124