COL(1) | General Commands Manual | COL(1)

# NAME

`col` — filter reverse line feeds and backspaces from input

# SYNOPSIS

`col` | [`-bfhx`] [`-l` num]

# 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 5 AT&T UNIX.

February 8, 2020 | Debian