NAME
col —
filter reverse line feeds from
input
SYNOPSIS
col |
[-bfhpx] [-l
num] |
DESCRIPTION
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:
-b- Do not output any backspaces, printing only the last character written to each column position.
-f- Forward half line feeds are permitted (``fine'' mode). Normally characters printed on a half line boundary are printed on the following line.
-h- Do not output multiple spaces instead of tabs (default).
-lnum- Buffer at least num lines in memory. By default, 128 lines are buffered.
-p- Force unknown control sequences to be passed through unchanged. Normally,
colwill filter out any control sequences from the input other than those recognized and interpreted by itself, which are listed below. -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:
- 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
-fmode, 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.
ENVIRONMENT
The LANG, LC_ALL
and LC_CTYPE environment variables affect the
execution of col as described in
environ(7).
EXIT STATUS
The col utility exits 0 on success,
and >0 if an error occurs.
EXAMPLES
We can use col to filter the output of
man(1) and
remove the backspace characters (
^H ) before
searching for some text:
man ls | col -b | grep HISTORY
SEE ALSO
STANDARDS
The col utility conforms to
Version 2 of the Single UNIX Specification
(“SUSv2”).
HISTORY
A col command appeared in
Version 6 AT&T UNIX.