col

PURPOSE

     Processes    text    having   reverse    linefeeds    and
     forward/reverse  half-linefeeds  for output  to  standard
     output.

SYNOPSIS
     col [ -bfpx ]


DESCRIPTION

     The col command  reads from standard input  and writes to
     standard output.   It performs the line  overlays implied
     by reverse  linefeeds (ASCII  ESC-7), and by  forward and
     reverse  half-linefeeds (ASCII  ESC-9  and ASCII  ESC-8).
     col  is particularly  useful  for filtering  multi-column
     output made by the nroff  .rt command and output from the
     tbl command.   The input  format accepted by  col matches
     the  output format  produced by  nroff -T37  or by  nroff
     -Tlp.  Use  -T37 and  the col  -f flag  if the  output is
     being  sent  to a  device  that  can interpret  half-line
     motions; use -Tlp otherwise.

     The col command assumes that the ASCII control characters
     SO (\017) and  SI (\016) begin and end text  in an alter-
     nate character set.  col remembers the character set each
     input character  belongs to,  and on output  generates SI
     and  SO characters  as  appropriate to  ensure that  each
     character is printed in the correct character set.

     On  input, col  accepts only  the control  characters for
     space,  backspace, tab,  return, the  new-line character,
     SI, SO, VT,  and ESC-7, 8, or 9.  VT  (\013) is an alter-
     nate form  of full reverse linefeed  included for compat-
     ibility  with some  earlier programs  of this  type.  col
     ignores all other non-printing characters.

     Notes:

     1.  The maximum number of lines  that can be backed up is
         128.

     2.  Up  to  800  characters,  including  backspaces,  are
         allowed on a line.

     3.  Local vertical  motions that would result  in backing
         up over the first line are ignored.  As a result, the
         first line must not contain any superscripts.

FLAGS

     -b    Assumes  that  the  output  device in  use  is  not
           capable of  backspacing.  In  this case, if  two or
           more characters are to appear in the same position,
           only the last one read appears in the output.
     -f    Suppresses  the  default   treatment  of  half-line
           motions in the input.   Normally, col does not emit
           half-line  motions  on  output,  although  it  does
           accept them  in its input.  With  this flag, output
           may contain forward  half-linefeeds (ESC-9) but not
           reverse linefeeds (ESC-7 or ESC-8).
     -p    Displays  unknown escape  sequences as  characters,
           subject to overprinting  from reverse line motions.
           Normally, col  ignores them.   You should  be fully
           aware of  the textual position of  escape sequences
           before you use this flag.
     -x    Suppresses  changing  the   white  space  to  tabs.
           Without this flag, col converts white space to tabs
           wherever doing so might shorten printing time.

RELATED INFORMATION

     The following commands:  "nroff, troff" and "tbl."

     The discussion of col in Text Formatting Guide.