SysIII/usr/src/man/man1/col.1

.TH COL 1
.SH NAME
col \- filter reverse line-feeds
.SH SYNOPSIS
.B col
[
.B \-bfpx
]
.SH DESCRIPTION
.I Col\^
reads from the standard input and writes onto the standard output.
It performs the line overlays implied by reverse line
feeds (\s-1ASCII\s+1 code \%\fB\s-1ESC\s+1-7\fP),
and by forward and reverse half-line-feeds (\fB\s-1ESC\s+1-9\fP and \fB\s-1ESC\s+1-8\fP).
.I Col\^
is particularly useful for filtering multicolumn
output made with the
.B \&.rt
command of
.IR nroff (1)
and output resulting from use of the
.IR tbl (1)
preprocessor.
.PP
If the
.B \-b
option is given,
.I col\^
assumes that the output device in use is not capable of backspacing.
In this case, if two or more characters are to appear in the same place,
only the last one read will be output.
.PP
Although
.I col\^
accepts half-line motions in its input, it normally does not
emit them on output.
Instead, text that would appear between lines is moved to the next lower
full-line boundary.
This treatment can be suppressed by the
.B \-f
(fine) option; in this case,
the output from
.I col\^
may contain forward half-line-feeds (\fB\s-1ESC\s+1-9\fP), but will still never contain
either kind of reverse line motion.
.PP
Unless the
.B \-x
option is given,
.I col\^
will convert white space to tabs on output
wherever possible to shorten printing time.
.PP
The \s-1ASCII\s+1 control characters \s-1\fBSO\fP\s+1 (\e017) and \s-1\fBSI\fP\s+1 (\e016) are assumed by
.I col\^
to start and end text in an alternate character set.
The character set to which each input character belongs is remembered,
and on output \s-1\fBSI\fP\s+1 and \s-1\fBSO\fP\s+1 characters are generated as appropriate to ensure
that each character is printed in the correct character set.
.PP
On input, the only control characters accepted are space, backspace,
tab, return, new-line, \s-1\fBSI\fP\s+1, \s-1\fBSO\fP\s+1, \s-1\fBVT\fP\s+1 (\e013),
and \fB\s-1ESC\s+1\fP followed by
.BR 7 ,
.BR 8 ,
or
.BR 9 .
The \s-1\fBVT\fP\s+1 character is an alternate form of full reverse line-feed,
included for
compatibility with some earlier programs of this type.
All other non-printing characters are ignored.
.PP
Normally,
.I col\^
will ignore any unknown to it escape sequences found in its input;
the
.B \-p
option may be used to cause
.I col\^
to output these sequences as regular characters, subject to overprinting
from reverse line motions.
The use of this option is highly discouraged unless the user
is fully aware of the textual position of the escape sequences.
.SH SEE ALSO
nroff(1), tbl(1).
.SH NOTES
The input format accepted by
.I col\^
matches the output produced by
.IR nroff (1)
with either the
.B \-T37
or
.B \-Tlp
options.
Use
.B \-T37
(and the
.B \-f
option of
.IR col )
if the ultimate disposition of the output of
.I col\^
will be a device
that can interpret half-line motions, and
.B \-Tlp
otherwise.
.SH BUGS
Cannot back up more than 128 lines.
.br
Allows at most 800 characters, including backspaces, on a line.
.br
Local vertical motions that would result in backing up over the first
line of the document are ignored.
As a result, the first line must not have any superscripts.