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)