COL(1) User Commands COL(1)

NAME

col - reverse line-feeds filter

SYNOPSIS

col [-bfpx]

DESCRIPTION

The col utility reads from the standard input and writes to the
standard output. It performs the line overlays implied by reverse
line-feeds, and by forward and reverse half-line-feeds. Unless -x is
used, all blank characters in the input will be converted to tab
characters wherever possible. col is particularly useful for
filtering multi-column output made with the .rt command of nroff(1)
and output resulting from use of the tbl(1) preprocessor.


The ASCII control characters SO and SI are assumed by col to start
and end text in an alternative character set. The character set to
which each input character belongs is remembered, and on output SI
and SO characters are generated as appropriate to ensure that each
character is written in the correct character set.


On input, the only control characters accepted are space, backspace,
tab, carriage-return and newline characters, SI, SO, VT, reverse
line-feed, forward half-line-feed and reverse half-line-feed. The VT
character is an alternative form of full reverse line-feed, included
for compatibility with some earlier programs of this type. The only
other characters to be copied to the output are those that are
printable.


The ASCII codes for the control functions and line-motion sequences
mentioned above are as given in the table below. ESC stands for the
ASCII escape character, with the octal code 033; ESC- means a
sequence of two characters, ESC followed by the character x.


reverse line-feed ESC-7
reverse half-line-feed ESC-8
forward half-line-feed ESC-9
vertical-tab (VT) 013
start-of-text (SO) 016
end-of-text (SI) 017

OPTIONS

-b
Assume 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.


-f
Although 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 -f
(fine) option; in this case, the output from col may contain
forward half-line-feeds (ESC-9), but will still never contain
either kind of reverse line motion.


-p
Normally, col will ignore any escape sequences unknown to it
that are found in its input; the -p option may be used to
cause 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.


-x
Prevent col from converting blank characters to tab characters
on output wherever possible. Tab stops are considered to be at
each column position n such that n modulo 8 equals 1.

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of col: LC_CTYPE, LC_MESSAGES,
and NLSPATH.

EXIT STATUS

The following error values are returned:

0
Successful completion.


>0
An error occurred.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|CSI | enabled |
+---------------+-----------------+

SEE ALSO

nroff(1), tbl(1), ascii(7), attributes(7), environ(7)

NOTES

The input format accepted by col matches the output produced by nroff
with either the -T37 or -Tlp options. Use -T37 (and the -f option of
col) if the ultimate disposition of the output of col will be a
device that can interpret half-line motions, and -Tlp otherwise.


col cannot back up more than 128 lines or handle more than 800
characters per line.


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.

February 1, 1995 COL(1)