1.\" Copyright (c) 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Michael Rendell. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd October 21, 2020 32.Dt COL 1 33.Os 34.Sh NAME 35.Nm col 36.Nd filter reverse line feeds from input 37.Sh SYNOPSIS 38.Nm 39.Op Fl bfhpx 40.Op Fl l Ar num 41.Sh DESCRIPTION 42The 43.Nm 44utility filters out reverse (and half reverse) line feeds so that the output is 45in the correct order with only forward and half forward line 46feeds, and replaces white-space characters with tabs where possible. 47.Pp 48The 49.Nm 50utility reads from the standard input and writes to the standard output. 51.Pp 52The options are as follows: 53.Bl -tag -width indent 54.It Fl b 55Do not output any backspaces, printing only the last character 56written to each column position. 57.It Fl f 58Forward half line feeds are permitted (``fine'' mode). 59Normally characters printed on a half line boundary are printed 60on the following line. 61.It Fl h 62Do not output multiple spaces instead of tabs (default). 63.It Fl l Ar num 64Buffer at least 65.Ar num 66lines in memory. 67By default, 128 lines are buffered. 68.It Fl p 69Force unknown control sequences to be passed through unchanged. 70Normally, 71.Nm 72will filter out any control sequences from the input other than those 73recognized and interpreted by itself, which are listed below. 74.It Fl x 75Output multiple spaces instead of tabs. 76.El 77.Pp 78In the input stream, 79.Nm 80understands both the escape sequences of the form escape-digit 81mandated by 82.St -susv2 83and the traditional 84.Bx 85format escape-control-character. 86The control sequences for carriage motion and their ASCII values 87are as follows: 88.Pp 89.Bl -tag -width "carriage return" -compact 90.It ESC\-BELL 91reverse line feed (escape then bell). 92.It ESC\-7 93reverse line feed (escape then 7). 94.It ESC\-BACKSPACE 95half reverse line feed (escape then backspace). 96.It ESC\-8 97half reverse line feed (escape then 8). 98.It ESC\-TAB 99half forward line feed (escape than tab). 100.It ESC\-9 101half forward line feed (escape then 9). 102In 103.Fl f 104mode, this sequence may also occur in the output stream. 105.It backspace 106moves back one column (8); ignored in the first column 107.It carriage return 108(13) 109.It newline 110forward line feed (10); also does carriage return 111.It shift in 112shift to normal character set (15) 113.It shift out 114shift to alternate character set (14) 115.It space 116moves forward one column (32) 117.It tab 118moves forward to next tab stop (9) 119.It vertical tab 120reverse line feed (11) 121.El 122.Pp 123All unrecognized control characters and escape sequences are 124discarded. 125.Pp 126The 127.Nm 128utility keeps track of the character set as characters are read and makes 129sure the character set is correct when they are output. 130.Pp 131If the input attempts to back up to the last flushed line, 132.Nm 133will display a warning message. 134.Sh ENVIRONMENT 135The 136.Ev LANG , LC_ALL 137and 138.Ev LC_CTYPE 139environment variables affect the execution of 140.Nm 141as described in 142.Xr environ 7 . 143.Sh EXIT STATUS 144.Ex -std 145.Sh EXAMPLES 146We can use 147.Nm 148to filter the output of 149.Xr man 1 150and remove the backspace characters ( 151.Em ^H 152) before searching for some text: 153.Bd -literal -offset indent 154man ls | col -b | grep HISTORY 155.Ed 156.Sh SEE ALSO 157.Xr expand 1 158.Sh STANDARDS 159The 160.Nm 161utility conforms to 162.St -susv2 . 163.Sh HISTORY 164A 165.Nm 166command 167appeared in 168.At v6 . 169