COL(1) General Commands Manual COL(1)

col — filter reverse line feeds from input

col [-bfhpx] [-l num]

The col utility 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 white-space characters with tabs where possible.

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

The options are as follows:

Do not output any backspaces, printing only the last character written to each column position.
Forward half line feeds are permitted (``fine'' mode). Normally characters printed on a half line boundary are printed on the following line.
Do not output multiple spaces instead of tabs (default).
num
Buffer at least num lines in memory. By default, 128 lines are buffered.
Force unknown control sequences to be passed through unchanged. Normally, col will filter out any control sequences from the input other than those recognized and interpreted by itself, which are listed below.
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:

ESC-BELL
reverse line feed (escape then bell).
ESC-7
reverse line feed (escape then 7).
ESC-BACKSPACE
half reverse line feed (escape then backspace).
ESC-8
half reverse line feed (escape then 8).
ESC-TAB
half forward line feed (escape than tab).
ESC-9
half forward line feed (escape then 9). 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.

The col utility 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.

The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of col as described in environ(7).

The col utility exits 0 on success, and >0 if an error occurs.

We can use col to filter the output of man(1) and remove the backspace characters ( ) before searching for some text:

man ls | col -b | grep HISTORY

expand(1)

The col utility conforms to Version 2 of the Single UNIX Specification (“SUSv2”).

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

October 21, 2020 macOS 15.0