# phpman > man > colcrt(1)

[COLCRT(1)](https://www.chedong.com/phpMan.php/man/COLCRT/1/markdown)                                   User Commands                                  [COLCRT(1)](https://www.chedong.com/phpMan.php/man/COLCRT/1/markdown)



## NAME
       colcrt - filter nroff output for CRT previewing

## SYNOPSIS
       **colcrt** [options] [_file_ ...]

## DESCRIPTION
       **colcrt** 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.

## OPTIONS
       **-**, **--no-underlining**
           Suppress all underlining. This option is especially useful for previewing _allboxed_ tables
           from [**tbl**(1)](https://www.chedong.com/phpMan.php/man/tbl/1/markdown).

### -2 --half-lines
           Causes 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.

### -V --version
           Display version information and exit.

### -h --help
           Display help text and exit.

## HISTORY
       The **colcrt** command appeared in 3.0BSD.

## BUGS
       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.

## EXAMPLES
       A typical use of **colcrt** would be:

          **tbl** **exum2.n** **|** **nroff** **-ms** **|** **colcrt** **-** **|** **more**

## SEE ALSO
       [**col**(1)](https://www.chedong.com/phpMan.php/man/col/1/markdown), [**more**(1)](https://www.chedong.com/phpMan.php/man/more/1/markdown), [**nroff**(1)](https://www.chedong.com/phpMan.php/man/nroff/1/markdown), [**troff**(1)](https://www.chedong.com/phpMan.php/man/troff/1/markdown), [**ul**(1)](https://www.chedong.com/phpMan.php/man/ul/1/markdown)

## REPORTING BUGS
       For bug reports, use the issue tracker at <https://github.com/karelzak/util-linux/issues>.

## AVAILABILITY
       The **colcrt** command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <<https://www.kernel.org/pub/linux/utils/util-linux/>>.



util-linux 2.37.2                            2021-06-02                                    [COLCRT(1)](https://www.chedong.com/phpMan.php/man/COLCRT/1/markdown)