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📛 NAME

colcrt - filter nroff output for CRT previewing

🚀 Quick Reference

Use Case	Command	Description
Suppress underlining	colcrt --no-underlining file	Remove underlining, convert to dashes
Double‑space output	colcrt -2 file	Print half‑lines, effectively double spacing
Filter nroff for CRT preview	tbl exum2.n | nroff -ms | colcrt - | more	Classic pipeline
Show version	colcrt --version	Display version information
Show help	colcrt --help	Display help text

🎯 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).

-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.

ℹ️ -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)
• more(1)
• nroff(1)
• troff(1)
• ul(1)

🐛 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/>.

📛 NAME 🚀 Quick Reference 🎯 SYNOPSIS 📘 DESCRIPTION ⚙️ OPTIONS 📜 HISTORY 🐞 BUGS 💻 EXAMPLES 🔗 SEE ALSO 🐛 REPORTING BUGS 📦 AVAILABILITY