COLCRT(1) General Commands Manual COLCRT(1)
colcrt – filter nroff output for CRT previewing
colcrt [-] [-2] [file ...]
The colcrt utility provides virtual half-line and reverse line feed
sequences for terminals without such capability, and on which overstriking
is destructive. Half-line characters and underlining (changed to dashing
`-') are placed on new lines in between the normal output lines.
The following options are available:
- Suppress all underlining. This option is especially useful for
previewing allboxed tables from tbl(1).
-2 Cause all half-lines to be printed, effectively double spacing the
output. Normally, a minimal space output format is used which will
suppress empty lines. The program never suppresses two consecutive
empty lines, however. The -2 option is useful for sending output
to the line printer when the output contains superscripts and
subscripts which would otherwise be invisible.
The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of
colcrt as described in environ(7).
A typical use of colcrt would be
tbl exum2.n | nroff -ms | colcrt - | more
The colcrt utility exits 0 on success, and >0 if an error occurs.
col(1), more(1), nroff(1), troff(1), ul(1)
Should fold underlines onto blanks even with the ‘-’ option so that a true
underline character would show.
Can't back up more than 102 lines.
General overstriking is lost; as a special case ‘|’ overstruck with ‘-’ or
underline becomes ‘+’.
Lines are trimmed to 132 characters.
Some provision should be made for processing superscripts and subscripts in
documents which are already double-spaced.
Characters that take up more than one column position may not be underlined
The colcrt command appeared in 3.0BSD.
macOS 12.1 July 31, 2004 macOS 12.1