colcrt - filter nroff output for CRT previewing


colcrt [] [-2] []


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.

Available options:
Suppress all underlining. This option is especially useful for previewing allboxed tables from tbl(1).
-2 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.


A typical use of colcrt would be tbl exum2.n | nroff -ms | colcrt - | more


nroff(1), troff(1), col(1), more(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.


The colcrt command appeared in BSD 3.0 .


The colcrt command is part of the util-linux-ng package and is available from

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