grn - Unix, Linux Command
grn - groff preprocessor for gremlin files
It is possible to have whitespace between a command line option and its
grn is a preprocessor for including
gremlin pictures in
grn writes to standard output, processing only input lines between two that
.GE. Those lines must contain
grn commands (see below).
These commands request a
gremlin file, and the picture in that file is
converted and placed in the
troff input stream.
.GS request may be followed by a C, L, or R to center, left, or right
justify the whole
gremlin picture (default justification is center).
file is mentioned, the standard input is read.
At the end of the picture, the position on the page is the bottom of the
grn entry is ended with
.GF instead of
.GE, the position is left at the top of the picture.
Please note that currently only the -me macro package has support for
.GS, .GE, and
The following command-line options are understood:
Prepare output for printer
dev. The default device is
for acceptable devices.
dir to the default search path for
The default path is (in that order) the current directory, the home
/usr/lib/groff/site-tmac, /usr/share/groff/site-tmac, and
dir for subdirectories
devname (name is the name of the device) for the
DESC file before the default font directories
/usr/share/groff/site-font, /usr/share/groff/18.104.22.168/font, and
.GF) even when followed by a character other than space or newline.
Print the version number.
Each input line between
.GE may have one
Commands consist of one or two strings separated by white space, the first
string being the command and the second its operand.
Commands may be upper or lower case and abbreviated down to one character.
Commands that affect a pictures environment (those listed before
default, see below) are only in effect for the current picture:
The environment is reinitialized to the defaults at the start of the next
The commands are as follows:
1 N ||
2 N ||
3 N ||
4 N ||
gremlins text size number 1 (2, 3, or 4) to
The default is 12 (resp. 16, 24, and 36).
roman f ||
italics f |
bold f ||
special f |
Set the roman (italics, bold, or special) font to
f (either a name or number).
The default is R (resp. I, B, and S).
l f ||
stipple f |
Set the stipple font to
troffs stipple font
f (name or number).
stipple may be abbreviated down as far as st (to avoid
special). There is
no default for stipples (unless one is set by the default command), and it is
invalid to include a
gremlin picture with polygons without specifying a
x N ||
scale N ||
Magnify the picture (in addition to any default magnification) by
N, a floating point number larger than zero.
scale may be abbreviated down to sc.
narrow N |
medium N |
thick N ||
Set the thickness of
gremlins narrow (resp. medium and thick) lines to
N times 0.15pt (this value can be changed at compile time).
The default is 1.0 (resp. 3.0 and 5.0), which corresponds to 0.15pt
(resp. 0.45pt and 0.75pt).
A thickness value of zero selects the smallest available line thickness.
Negative values cause the line thickness to be proportional to the current
pointscale <off/on> |
Scale text to match the picture.
Gremlin text is usually printed in the point size specified with the
1, 2, 3, or 4 regardless of any scaling factors in the picture.
pointscale will cause the point sizes to scale with the picture (within
troffs limitations, of course).
An operand of anything but
off will turn text scaling on.
Reset the picture environment defaults to the settings in the current
This is meant to be used as a global parameter setting mechanism at the
beginning of the
troff input file, but can be used at any time to reset the
width N ||
Forces the picture to be
N inches wide.
This overrides any scaling factors present in the same picture.
width 0 is ignored.
height N |
Forces picture to be
N inches high, overriding other scaling factors.
If both width and height are specified the tighter constraint will
determine the scale of the picture.
width commands are not saved with a
They will, however, affect point size scaling if that option is set.
file name |
Get picture from
name located the current directory (or in the library directory; see the
-M option above).
file commands are given, the second one overrides the first.
name doesnt exist, an error message is reported and processing continues from
NOTES ABOUT GROFF
grn is a preprocessor, it doesnt know about current indents, point sizes,
margins, number registers, etc.
troff input can be placed between the
gremlin text is now processed by
troff, so anything legal in a single line of
troff input is legal in a line of
gremlin text (barring . directives at the beginning of a line).
Thus, it is possible to have equations within a
gremlin figure by including in the
eqn expressions enclosed by previously defined delimiters (e.g.
grn along with other preprocessors, it is best to run
grn, pic, and/or
ideal to avoid overworking
tbl. Eqn should always be run last.
A picture is considered an entity, but that doesnt stop
troff from trying to break it up if it falls off the end of a page.
Placing the picture between keeps in -me macros will ensure proper
troffs number registers
g9 and sets registers
g2 to the width and height of the
gremlin figure (in device units) before entering the
.GS request (this is for those who want to rewrite these macros).
GREMLIN FILE FORMAT
There exist two distinct
gremlin file formats, the original format from the
AED graphic terminal version, and the
An extension to the
SUN/X11 version allowing reference points with negative coordinates is
not compatible with the
As long as a
gremlin file does not contain negative coordinates, either format will be read
correctly by either version of
grn. The other difference to the
SUN/X11 format is the use of names for picture objects (e.g., POLYGON, CURVE)
instead of numbers.
Files representing the same picture are shown in Table 1 in each format.
|0 240.00 128.00|| ||0 240.00 128.00|
|240.00 128.00|| ||240.00 128.00|
|185.00 120.00|| ||185.00 120.00|
|240.00 120.00|| ||240.00 120.00|
|296.00 120.00|| ||296.00 120.00|
|*|| ||-1.00 -1.00|
|2 3|| ||2 3|
|10 A Triangle|| ||10 A Triangle|
|224.00 416.00|| ||224.00 416.00|
|96.00 160.00|| ||96.00 160.00|
|384.00 160.00|| ||384.00 160.00|
|*|| ||-1.00 -1.00|
|5 1|| ||5 1|
|Table 1. File examples|
The first line of each
gremlin file contains either the string
gremlinfile (AED version) or
sungremlinfile (SUN/X11) |
The second line of the file contains an orientation, and
y values for a positioning point, separated by spaces.
The orientation, either
1, is ignored by the
0 means that
gremlin will display things in horizontal format (drawing area wider than it is
tall, with menu across top).
1 means that
gremlin will display things in vertical format (drawing area taller than it is wide,
with menu on left side).
y are floating point values giving a positioning point to be used when this
file is read into another file.
The stuff on this line really isnt all that important; a value of 1 0.00
0.00 is suggested.
The rest of the file consists of zero or more element specifications.
After the last element specification is a line containing the string -1.
Lines longer than 127 characters are chopped to this limit.
The first line of each element contains a single decimal number giving the
type of the element
(AED version) or its ASCII name
See Table 2.
|gremlin File Format - Object Type Specification|
|AED Number||SUN/X11 Name||Description|
|Type Specifications in gremlin Files|
After the object type comes a variable number of lines, each specifying a
point used to display the element.
Each line contains an x-coordinate and a y-coordinate in floating point
format, separated by spaces.
The list of points is terminated by a line containing the string -1.0
(AED version) or a single asterisk, *
After the points comes a line containing two decimal values, giving the
brush and size for the element.
The brush determines the style in which things are drawn.
For vectors, arcs, and curves there are six legal brush values:
|1 -|| ||thin dotted lines|
|2 -|| ||thin dot-dashed lines|
|3 -|| ||thick solid lines|
|4 -|| ||thin dashed lines|
|5 -|| ||thin solid lines|
|6 -|| ||medium solid lines|
For polygons, one more value, 0, is legal.
It specifies a polygon with an invisible border.
For text, the brush selects a font as follows:
|1 -|| ||roman (R font in groff)|
|2 -|| ||italics (I font in groff)|
|3 -|| ||bold (B font in groff)|
|4 -|| ||special (S font in groff)|
If youre using
grn to run your pictures through
groff, the font is really just a starting font:
The text string can contain formatting sequences like
which may change the font (as well as do many other things).
For text, the size field is a decimal value between 1 and 4.
It selects the size of the font in which the text will be drawn.
For polygons, this size field is interpreted as a stipple number to fill the
The number is used to index into a stipple font at print time.
The last line of each element contains a decimal number and a string of
characters, separated by a single space.
The number is a count of the number of characters in the string.
This information is only used for text elements, and contains the text
There can be spaces inside the text.
For arcs, curves, and vectors, this line of the element contains the string
NOTES ON COORDINATES
gremlin was designed for
AEDs, and its coordinates reflect the
AED coordinate space.
For vertical pictures, x-values range 116 to 511, and y-values from 0 to
For horizontal pictures, x-values range from 0 to 511 and y-values range
from 0 to 367.
Although you neednt absolutely stick to this range, youll get best results
if you at least stay in this vicinity.
Also, point lists are terminated by a point of (-1, -1), so you shouldnt
ever use negative coordinates.
gremlin writes out coordinates using format %f1.2; its probably a good idea to
use the same format if you want to modify the
NOTES ON SUN/X11 COORDINATES
There is no longer a restriction on the range of coordinates used to create
objects in the
SUN/X11 version of
gremlin. However, files with negative coordinates
will cause problems if displayed on the
Device description file for device
David Slattengren and Barry Roitblat wrote the original Berkeley
Daniel Senderowicz and Werner Lemberg modified it for