


      COL(1)                        (DWB)                        COL(1)



      NAME
           col - filter reverse line-feeds

      SYNTAX
           col [ -bfpx ]

      DESCRIPTION
           Col reads from the standard input and writes onto the
           standard output.  It performs the line overlays implied by
           reverse line feeds (ASCII code ESC-7), and by forward and
           reverse half-line-feeds (ESC-9 and ESC-8).  Col is
           particularly useful for filtering multicolumn output made
           with the .rt command of nroff and output resulting from use
           of the tbl(1) preprocessor.

           If the -b option is given, col 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 place,
           only the last one read will be output.

           Although col accepts half-line motions in its input, it
           normally does not emit them on output.  Instead, text that
           would appear between lines is moved to the next lower full-
           line boundary.  This treatment can be suppressed by the -f
           (fine) option; in this case, the output from col may contain
           forward half-line-feeds (ESC-9), but will still never
           contain either kind of reverse line motion.

           Unless the -x option is given, col will convert white space
           to tabs on output wherever possible to shorten printing
           time.

           The ASCII control characters SO (\017) and SI (\016) are
           assumed by col to start and end text in an alternate
           character set.  The character set to which each input
           character belongs is remembered, and on output SI and SO
           characters are generated as appropriate to ensure that each
           character is printed in the correct character set.

           On input, the only control characters accepted are space,
           backspace, tab, return, new-line, SI, SO, VT (\013), and ESC
           followed by 7, 8, or 9.  The VT character is an alternate
           form of full reverse line-feed, included for compatibility
           with some earlier programs of this type.  All other non-
           printing characters are ignored.

           Normally, col will ignore any unknown to it escape sequences
           found in its input; the -p option may be used to cause col
           to output these sequences as regular characters, subject to
           overprinting from reverse line motions.  The use of this
           option is highly discouraged unless the user is fully aware
           of the textual position of the escape sequences.



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      COL(1)                        (DWB)                        COL(1)



      SEE ALSO
           nroff(1), tbl(1).

      NOTES
           The input format accepted by col matches the output produced
           by nroff with either the -T37 or -Tlp options.  Use -T37
           (and the -f option of col) if the ultimate disposition of
           the output of col will be a device that can interpret half-
           line motions, and -Tlp otherwise.

      BUGS
           Cannot back up more than 128 lines.
           Allows at most 800 characters, including backspaces, on a
           line.
           Local vertical motions that would result in backing up over
           the first line of the document are ignored.  As a result,
           the first line must not have any superscripts.






































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