8a27a63745
Add a small example. Cross reference clean up for colcrt, nroff and tbl. Reviewed by: gbe@, bcr@ Approved by: gbe@ Differential Revision: https://reviews.freebsd.org/D26864
172 lines
4.7 KiB
Groff
172 lines
4.7 KiB
Groff
.\" Copyright (c) 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Michael Rendell.
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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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.\" @(#)col.1 8.1 (Berkeley) 6/29/93
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.\" $FreeBSD$
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.\"
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.Dd October 21, 2020
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.Dt COL 1
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.Os
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.Sh NAME
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.Nm col
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.Nd filter reverse line feeds from input
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.Sh SYNOPSIS
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.Nm
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.Op Fl bfhpx
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.Op Fl l Ar num
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.Sh DESCRIPTION
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The
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.Nm
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utility filters out reverse (and half reverse) line feeds so that the output is
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in the correct order with only forward and half forward line
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feeds, and replaces white-space characters with tabs where possible.
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.Pp
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The
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.Nm
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utility reads from the standard input and writes to the standard output.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl b
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Do not output any backspaces, printing only the last character
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written to each column position.
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.It Fl f
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Forward half line feeds are permitted (``fine'' mode).
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Normally characters printed on a half line boundary are printed
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on the following line.
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.It Fl h
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Do not output multiple spaces instead of tabs (default).
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.It Fl l Ar num
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Buffer at least
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.Ar num
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lines in memory.
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By default, 128 lines are buffered.
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.It Fl p
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Force unknown control sequences to be passed through unchanged.
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Normally,
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.Nm
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will filter out any control sequences from the input other than those
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recognized and interpreted by itself, which are listed below.
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.It Fl x
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Output multiple spaces instead of tabs.
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.El
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.Pp
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In the input stream,
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.Nm
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understands both the escape sequences of the form escape-digit
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mandated by
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.St -susv2
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and the traditional
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.Bx
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format escape-control-character.
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The control sequences for carriage motion and their ASCII values
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are as follows:
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.Pp
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.Bl -tag -width "carriage return" -compact
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.It ESC\-BELL
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reverse line feed (escape then bell).
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.It ESC\-7
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reverse line feed (escape then 7).
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.It ESC\-BACKSPACE
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half reverse line feed (escape then backspace).
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.It ESC\-8
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half reverse line feed (escape then 8).
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.It ESC\-TAB
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half forward line feed (escape than tab).
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.It ESC\-9
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half forward line feed (escape then 9).
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In
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.Fl f
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mode, this sequence may also occur in the output stream.
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.It backspace
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moves back one column (8); ignored in the first column
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.It carriage return
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(13)
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.It newline
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forward line feed (10); also does carriage return
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.It shift in
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shift to normal character set (15)
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.It shift out
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shift to alternate character set (14)
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.It space
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moves forward one column (32)
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.It tab
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moves forward to next tab stop (9)
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.It vertical tab
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reverse line feed (11)
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.El
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.Pp
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All unrecognized control characters and escape sequences are
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discarded.
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.Pp
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The
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.Nm
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utility keeps track of the character set as characters are read and makes
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sure the character set is correct when they are output.
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.Pp
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If the input attempts to back up to the last flushed line,
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.Nm
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will display a warning message.
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.Sh ENVIRONMENT
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The
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.Ev LANG , LC_ALL
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and
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.Ev LC_CTYPE
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environment variables affect the execution of
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.Nm
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as described in
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.Xr environ 7 .
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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We can use
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.Nm
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to filter the output of
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.Xr man 1
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and remove the backspace characters (
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.Em ^H
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) before searching for some text:
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.Bd -literal -offset indent
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man ls | col -b | grep HISTORY
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.Ed
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.Sh SEE ALSO
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.Xr expand 1
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.Sh STANDARDS
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The
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.Nm
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utility conforms to
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.St -susv2 .
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.Sh HISTORY
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A
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.Nm
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command
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appeared in
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.At v6 .
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