-.TH COL 1 ""
-.AT 3
-.SH NAME
-col \- filter reverse line feeds
-.SH SYNOPSIS
-.B col
-[
-.B \-bfh
-]
-.SH DESCRIPTION
-.I Col
-reads the standard input and writes the standard output.
-It performs the line overlays implied by reverse line
-feeds (ESC-7 in ASCII)
-and by forward and reverse half line feeds (ESC-9 and ESC-8).
-.I Col
-is particularly useful for filtering multicolumn
-output made with the `.rt' command of
-.I nroff
-and output resulting from use of the
-.IR tbl (1)
-preprocessor.
-.PP
-Although
-.I 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
-.B \-f
-(fine) option; in this case
-the output from
-.I col
-may contain forward half line feeds (ESC-9), but will still never contain
-either kind of reverse line motion.
-.PP
-If the
-.B \-b
-option is given,
-.I col
-assumes that the output device in use is not capable of backspacing.
-In this case, if several characters are to appear in the same place,
-only the last one read will be taken.
-.PP
-The control characters SO (ASCII code 017),
-and SI (016) are assumed
-to start and end text in an alternate character set.
-The character set (primary or alternate) associated with each printing
-character read is remembered; on output, SO and SI characters are generated
-where necessary to maintain the correct treatment of each character.
-.PP
-If the
-.B \-h
-option is given,
-.I col
-converts white space to tabs to shorten printing time.
-.PP
-All control characters are removed from the input except space,
-backspace,
-tab, return, newline, ESC (033) followed by one of 7, 8, 9, SI, SO, and VT
-(013).
-This last character is an alternate form of full reverse line feed, for
-compatibility with some other hardware conventions.
-All other non-printing characters are ignored.
-.SH "SEE ALSO"
-troff(1), tbl(1)
-.SH BUGS
-Can't back up more than 128 lines.
-.br
-No more than 800 characters, including backspaces, on a line.
+.\" This code is derived from software contributed to Berkeley by
+.\" Michael Rendell.
+.\"
+.\" %sccs.include.redist.man%
+.\"
+.\" @(#)col.1 6.7 (Berkeley) %G%
+.\"
+.Dd
+.Dt COL 1
+.Os
+.Sh NAME
+.Nm col
+.Nd filter reverse line feeds from input
+.Sh SYNOPSIS
+.Nm col
+.Op Fl bfx
+.Op Fl l Ar num
+.Sh DESCRIPTION
+.Nm Col
+filters out reverse (and half reverse) line feeds so the output is
+in the correct order with only forward and half forward line
+feeds, and replaces white-space characters with tabs where possible.
+This can be useful in processing the output of
+.Xr nroff 1
+and
+.Xr tbl 1 .
+.Pp
+.Nm Col
+reads from standard input and writes to standard output.
+.Pp
+The options are as follows:
+.Bl -tag -width "-lnum"
+.It Fl b
+Do not output any backspaces \- print only the last character
+written to each column position.
+.It Fl f
+Forward half line feeds are permitted (``fine'' mode).
+Normally characters printed on a half line boundary are printed
+on the following line.
+.It Fl x
+Output multiple spaces instead of tabs.
+.It Fl l Ns Ar num
+Buffer at least
+.Ar num
+lines in memory.
+By default, 128 lines are buffered.
+.El
+.Pp
+The control sequences for carriage motion that
+.Nm col
+understands and their decimal values are listed in the following
+table:
+.Pp
+.Bl -tag -width "carriage return" -compact
+.It ESC\-7
+reverse line feed (escape then 7)
+.It ESC\-8
+half reverse line feed (escape then 8)
+.It ESC\-9
+half forward line feed (escape then 9)
+.It backspace
+moves back one column (8); ignored in the first column
+.It carriage return
+(13)
+.It newline
+forward line feed (10); also does carriage return
+.It shift in
+shift to normal character set (15)
+.It shift out
+shift to alternate character set (14)
+.It space
+moves forward one column (32)
+.It tab
+moves forward to next tab stop (9)
+.It vertical tab
+reverse line feed (11)
+.El
+.Pp
+All unrecognized control characters and escape sequences are
+discarded.
+.Pp
+.Nm Col
+keeps track of the character set as characters are read and makes
+sure the character set is correct when they are output.
+.Pp
+If the input attempts to back up to the last flushed line,
+.Nm col
+will display a warning message.
+.Sh SEE ALSO
+.Xr expand 1 ,
+.Xr nroff 1 ,
+.Xr tbl 1
+.Sh HISTORY
+A
+.Nm col
+command
+appeared in Version 6 AT&T UNIX. The
+.Bx
+.Nm col
+is derived from code written by Michael Rendell.
projects / unix-history / blobdiff