col.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH col 1
.SH Name
col \- filter reverse line feeds
.SH Syntax
.B col [\fI\-options\fR]
.SH Description
.NXR "col command"
.NXR "line feed" "reversing"
The
.PN col
command
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,
respectively).
The 
.PN col
command
is particularly useful for filtering multicolumn
output made with the 
.PN \&.rt
command of
.PN nroff ,
and for filtering output resulting from the
.PN tbl
preprocessor.
.NXR "column" "filtering multiple"
.PP
Although
.PN col
accepts half line motions in its input, it does not
normally output them.
Instead, text that would appear between lines is moved to the next lower
full line boundary.
.PP
The control characters SO (ASCII code 017)
and SI (ASCII code 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
The
.PN col
command
normally converts white space to tabs to shorten printing time.
If the
.B \-h
option is given, this conversion is suppressed.
.PP
On input, the only control characters accepted are <space>,
<backspace>, <tab>, <return>, <newline>, etc...  The VT
character is an alternate form of full reverse linefeed, included
for compatibility with earlier programs of this type. All other
non-printing characters are ignored.
.SH Options
.IP \fB\-b\fR
Assumes that the output device does not have backspacing.  
.IP \fB\-f\fR 
Suppresses moving half lines to the next full line.  
.IP \fB\-h\fR 
Suppresses conversion of white space to tabs.  
.IP \fB\-p\fR
Forces through unchanged any unknown escape sequences
that are found in its input. This option should be used with care.
.IP \fB\-x\fR
Suppresses conversion of white space to tabs (same as \-h).
.SH Restrictions
.NXR "col command" "restricted"
Cannot back up more than 128 lines.
.br
No more than 800 characters, including backspaces, on a line.
.SH See Also
tbl(1), nroff(1)