.\" Copyright (c) 1990 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Michael Rendell.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)col.1	6.8 (Berkeley) 06/17/91
.\"
.Dd 
.Dt COL 1
.Os
.Sh NAME
.Nm col
.Nd filter reverse line feeds from input
.Sh SYNOPSIS
.Nm col
.Op Fl bfx
.Op Fl l Ar num
.Sh DESCRIPTION
.Nm Col
filters out reverse (and half reverse) line feeds so the output is
in the correct order with only forward and half forward line
feeds, and replaces white-space characters with tabs where possible.
This can be useful in processing the output of
.Xr nroff 1
and
.Xr tbl  1 .
.Pp
.Nm Col
reads from standard input and writes to standard output.
.Pp
The options are as follows:
.Bl -tag -width "-lnum"
.It Fl b
Do not output any backspaces, printing only the last character
written to each column position.
.It Fl f
Forward half line feeds are permitted (``fine'' mode).
Normally characters printed on a half line boundary are printed
on the following line.
.It Fl x
Output multiple spaces instead of tabs.
.It Fl l Ns Ar num
Buffer at least
.Ar num
lines in memory.
By default, 128 lines are buffered.
.El
.Pp
The control sequences for carriage motion that
.Nm col
understands and their decimal values are listed in the following
table:
.Pp
.Bl -tag -width "carriage return" -compact
.It ESC\-7
reverse line feed (escape then 7)
.It ESC\-8
half reverse line feed (escape then 8)
.It ESC\-9
half forward line feed (escape then 9)
.It backspace
moves back one column (8); ignored in the first column
.It carriage return
(13)
.It newline
forward line feed (10); also does carriage return
.It shift in
shift to normal character set (15)
.It shift out
shift to alternate character set (14)
.It space
moves forward one column (32)
.It tab
moves forward to next tab stop (9)
.It vertical tab
reverse line feed (11)
.El
.Pp
All unrecognized control characters and escape sequences are
discarded.
.Pp
.Nm Col
keeps track of the character set as characters are read and makes
sure the character set is correct when they are output.
.Pp
If the input attempts to back up to the last flushed line,
.Nm col
will display a warning message.
.Sh SEE ALSO
.Xr expand 1 ,
.Xr nroff 1 ,
.Xr tbl 1
.Sh HISTORY
A
.Nm col
command
appeared in Version 6 AT&T UNIX.