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NAME

col — filter reverse line feeds and backspaces from input

SYNOPSIS

DESCRIPTION

col filters out reverse (and half-reverse) line feeds so that the output is in the correct order with only forward and half-forward line feeds, and replaces whitespace characters with tabs where possible.

col reads from the standard input and writes to the standard output.

The options are as follows:

-b

Do not output any backspaces, printing only the last character written to each column position. This can be useful in processing the output of mandoc(1).

-f

Forward half-line feeds are permitted (“fine” mode). Normally characters printed on a half-line boundary are printed on the following line.

-h

Compress spaces into tabs. This is the default behavior.

-l num

Buffer at least num lines in memory. By default, 128 lines are buffered.

-x

Output multiple spaces instead of tabs.

In the input stream, col understands both the escape sequences of the form escape-digit mandated by Version 2 of the Single UNIX Specification (“SUSv2”) and the traditional BSD format escape-control-character. The control sequences for carriage motion and their ASCII values are as follows:

escape-bell

Reverse line feed (27 then 7).

escape-digit-7

Reverse line feed (27 then 55).

escape-backspace

Half reverse line feed (27 then 8).

escape-digit-8

Half reverse line feed (27 then 56).

escape-tab

Half forward line feed (27 then 9).

escape-digit-9

Half forward line feed (27 then 57). In -f mode, this sequence may also occur in the output stream.

backspace

Moves back one column (8); ignored in the first column.

carriage return

(13)

newline

Forward line feed (10); also does carriage return.

shift in

Shift to normal character set (15).

shift out

Shift to alternate character set (14).

space

Moves forward one column (32).

tab

Moves forward to next tab stop (9).

vertical tab

Reverse line feed (11).

All unrecognized control characters and escape sequences are discarded.

col keeps track of the character set as characters are read and makes sure the character set is correct when they are output.

If the input attempts to back up to the last flushed line, col will display a warning message.

SEE ALSO

expand(1)

HISTORY

A col command appeared in Version 6 AT&T UNIX.