col -- Command

Remove reverse and half-line motions
col [ -bdfx ][ -pn ]

The command col reads the standard input and writes to the standard output.
It removes reverse  and half-line motions from the output  of nroff for the
benefit of output devices that  cannot perform them.  It maintains an image
of the page  in memory and performs these motions  virtually so they do not
appear on the output.

col understands four escape sequences: <esc> 7 for reverse line feed,
<esc> 8  for half reverse  line feed, <esc> 9  for half forward
line  feed,  and  <esc>  B  for  a forward  line  feed.   It  removes
<esc> (ASCII  033) from  the input  stream if it  is followed  by any
other character.

Eight  control  characters  besides  <esc>  are interpreted  by  col.
Newline, return,  space, backspace, and tab carry  their usual meaning.  VT
(013) is an  alternate form of reverse line feed.   The characters SO (017)
and SI  (016) signal the  start and end  of text in  an alternate character
set.  col remembers the character set for each character and uses SO and SI
to  distinguish  them  on  the  output.   col  removes  all  other  control
characters from the input stream.

col recognizes the following options:

-b  The  output  device  cannot backspace.   Only  the  last  of  a set  of
    characters destined for a given position will appear.

-d  Double-space the  output.  This  doubles the  length of a  document but
    preserves relative vertical spacing.  The -f option has precedence.

-f  The  output device  can perform  half-forward  line feeds.   Full lines
    appear single  spaced with half  lines between them.  This  is the only
    situation in which half forward line  feeds appear in the output of col
    -- reverse line motions never appear.

-x  Suppress the default conversion of white space to tabs on output.

-p n
    Set the internal page buffer size to n full lines (default, 128).

If neither -f nor -d is  chosen, col moves non-empty half lines to the next
lower full line and pushes all later lines down one line.  This can distort
the appearance of the document.

See Also

ASCII,
commands,
nroff

Notes

Backing  up past  the  start of  a  document or  of the  page buffer  loses
characters.

© 2012 by Stephen A. Ness