Go Roff Extension Util

greu is an utility to quickly enhance troff with custom commands

Usage

greu is yet another preprocessor to roff, you can use greu in any position in your pipeline but you want to use as the first one, for example:

cat input.roff | greu | eqn | roff > output.ps

Commands

greu defines the commands in a config, the primary fields are:

Name	Meaning	Example
Cmd	The shell command to execute	gnuplot
Args	The shell arguments	-d
OpenTag	The opening tag detected in the input file by greu	.GNUPLOTSTART
CloseTag	The closing tag detected in the input file by greu	.GNUPLOTEND
ReplaceOpenTag	A string that will be inserted in the output before the command output	.PS
ReplaceCloseTag	A string that will be inserted in the output after the command output	.PE
InputPrefix	A string that will be passed to the command before the input file lines, usefull for some prelude	set terminal eps
InputPostfix	A string that will be passed to the command before closing, usefull to exit	exit
IgnoreStdOut	Ignore the output of the command, usefull when the output is a file, see GREU_TMP	true

Variables

Most values can use some special variable, all replace automatically by greu

Name	Meaning	Example
GREU_TMP	A temp file that the program can freely use, it will be cancelled after the program exit	ReplaceCloseTag: .PSPIC GREU_TMP

Example

Let's say that we want to incorportate gnuplot graphs in our document and that our roff implementation has a .PS/.PE commands to include raw eps.

Cmd: gnuplot
OpenTag: .GNUPLOTSTART
CloseTag: .GNUPLOTEND
ReplaceOpenTag: .PS
ReplaceCloseTag: .PE
InputPrefix: set terminal eps
InputPostfix: exit

Now we can write our document:

Commodo excepteur fugiat non deserunt laboris nisi culpa sit.
.GNUPLOTSTART
plot sin(x)
.GNUPLOTEND
Do consectetur laborum minim exercitation amet minim sit laboris adipisicing exercitation proident labore proident labore.

After passing in greu the output will be:

Commodo excepteur fugiat non deserunt laboris nisi culpa sit.
.PS
%!PS-Adobe-3.0 EPSF-3.0
%%Creator: cairo 1.17.6 (https://cairographics.org)
%%CreationDate: Sun Dec 25 13:17:18 2022
%%Pages: 1
%%DocumentData: Clean7Bit
%%LanguageLevel: 2
%%BoundingBox: 0 0 360 216
%%EndComments
%%BeginProlog
...
.PE
Do consectetur laborum minim exercitation amet minim sit laboris adipisicing exercitation proident labore proident labore.

How it works