grn(1) — Linux manual page

Name | Synopsis | Description | Options | Files | Authors | See also | COLOPHON

grn(1)                   General Commands Manual                  grn(1)

Name         top

       grn - embed gremlin images in groff documents

Synopsis         top

       grn [-C] [-T dev] [-M dir] [-F dir] [file ...]

       grn -?
       grn --help

       grn -v
       grn --version

Description         top

       grn is a preprocessor for including gremlin pictures in troff(1)
       input.  grn writes to standard output, processing only input
       lines between two that start with .GS and .GE.  Those lines must
       contain grn commands (see below).  These macros request a gremlin
       file; the picture in that file is converted and placed in the
       troff input stream.  .GS may be called with a C, L, or R argument
       to center, left-, or right-justify the whole gremlin picture (the
       default is to center).  If no file is mentioned, the standard
       input is read.  At the end of the picture, the position on the
       page is the bottom of the gremlin picture.  If the grn entry is
       ended with .GF instead of .GE, the position is left at the top of
       the picture.

       Currently only the me macro package has support for .GS, .GE, and

       grn produces drawing escape sequences that use groff's color
       scheme extension (\D'F ...'), and thus may not work with other

   grn commands
       Each input line between .GS and .GE may have one grn command.
       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 lowercase and abbreviated down to one

       Commands that affect a picture's 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 picture.  The commands are as follows.

       1 N
       2 N
       3 N
       4 N    Set gremlin's text size number 1 (2, 3, or 4) to N points.
              The default is 12 (16, 24, and 36, respectively).

       roman f
       italics f
       bold f
       special f
              Set the roman (italics, bold, or special) font to troff's
              font f (either a name or number).  The default is R (I, B,
              and S, respectively).

       l f
       stipple f
              Set the stipple font to troff's stipple font f (name or
              number).  The command stipple may be abbreviated down as
              far as “st” (to avoid confusion with “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 stipple font.

       x N
       scale N
              Magnify the picture (in addition to any default
              magnification) by N, a floating-point number larger than
              zero.  The command scale may be abbreviated down to “sc”.

       narrow N
       medium N
       thick N
              Set the thickness of gremlin's narrow (medium and thick,
              respectively) lines to N times 0.15pt (this value can be
              changed at compile time).  The default is 1.0 (3.0 and
              5.0, respectively), which corresponds to 0.15pt (0.45pt
              and 0.75pt, respectively).  A thickness value of zero
              selects the smallest available line thickness.  Negative
              values cause the line thickness to be proportional to the
              current point size.

       pointscale [off|on]
              Scale text to match the picture.  Gremlin text is usually
              printed in the point size specified with the commands 1,
              2, 3, or 4, regardless of any scaling factors in the
              picture.  Setting pointscale will cause the point sizes to
              scale with the picture (within troff's 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 picture.  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
              default settings.

       width N
              Force the picture to be N inches wide.  This overrides any
              scaling factors present in the same picture.  “width 0” is

       height N
              Force the 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.  height and width commands are not saved with a
              “default” command.  They will, however, affect point size
              scaling if that option is set.

       file name
              Get picture from gremlin file name located the current
              directory (or in the library directory; see the -M option
              above).  If multiple file commands are given, the last one
              controls.  If name doesn't exist, an error message is
              reported and processing continues from the .GE line.

   Usage with groff
       Since grn is a preprocessor, it doesn't know about current
       indentation, point sizes, margins, registers, and so on.
       Consequently, no troff input can be placed between the .GS and
       .GE macros.  However, gremlin text is now processed by troff, so
       anything valid in a single line of troff input is valid in a line
       of gremlin text (barring the dot control character “.” at the
       beginning of a line).  Thus, it is possible to have equations
       within a gremlin figure by including in the gremlin file eqn
       expressions enclosed by previously defined delimiters (e.g.,

       When using grn along with other preprocessors, it is best to run
       tbl(1) before grn, pic(1), and/or ideal to avoid overworking tbl.
       eqn(1) should always be run last.

       A picture is considered an entity, but that doesn't stop troff
       from trying to break it up if it falls off the end of a page.
       Placing the picture between “keeps” in the me macros will ensure
       proper placement.

       grn uses troff's number registers g1 through g9 and sets
       registers g1 and g2 to the width and height of the gremlin figure
       (in device units) before entering the .GS macro (this is for
       those who want to rewrite these macros).

   Gremlin file format
       There exist two distinct gremlin file formats: the original
       format for AED graphic terminals, and the Sun or X11 version.  An
       extension used by the Sun/X11 version allowing reference points
       with negative coordinates is not compatible with the AED version.
       As long as a gremlin file does not contain negative coordinates,
       either format will be read correctly by either version of gremlin
       or grn.  The other difference in 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.

                     sungremlinfile        gremlinfile
                     0 240.00 128.00       0 240.00 128.00
                     CENTCENT              2
                     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
                     POLYGON               6
                     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
                     0                     0
                     -1                    -1

                            Table 1.  File examples

       •      The first line of each gremlin file contains either the
              string “gremlinfile” (AED) or “sungremlinfile” (Sun/X11).

       •      The second line of the file contains an orientation and x
              and y values for a positioning point, separated by spaces.
              The orientation, either 0 or 1, is ignored by the Sun/X11
              version.  0 means that gremlin will display things in
              horizontal format (a drawing area wider than it is tall,
              with a menu across the top).  1 means that gremlin will
              display things in vertical format (a drawing area taller
              than it is wide, with a menu on the left side).  x and 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 isn't 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 truncated to that

   Element specifications
       •      The first line of each element contains a single decimal
              number giving the type of the element (AED) or its name

                    gremlin File Format: Object Type Specification
               AED Number   Sun/X11 Name           Description
                    0       BOTLEFT        bottom-left-justified text
                    1       BOTRIGHT       bottom-right-justified text
                    2       CENTCENT       center-justified text
                    3       VECTOR         vector
                    4       ARC            arc
                    5       CURVE          curve
                    6       POLYGON        polygon
                    7       BSPLINE        b-spline
                    8       BEZIER         Bézier
                   10       TOPLEFT        top-left-justified text
                   11       TOPCENT        top-center-justified text
                   12       TOPRIGHT       top-right-justified text
                   13       CENTLEFT       left-center-justified text
                   14       CENTRIGHT      right-center-justified text
                   15       BOTCENT        bottom-center-justified text

                    Table 2.  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
              -1.0” (AED) or a single asterisk, “*” (Sun/X11).

       •      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 valid brush

                              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 valid.  It specifies a
              polygon with an invisible border.  For text, the brush
              selects a font as follows.

                            1   roman (R font in troff)
                            2   italics (I font in troff)
                            3   bold (B font in troff)
                            4   special (S font in troff)

              If you're using grn to run your pictures through groff,
              the font is really just a starting font.  The text string
              can contain formatting sequences like “\fI” or “\d” 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 polygon with.  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 used only for text elements,
              and contains the text string.  There can be spaces inside
              the text.  For arcs, curves, and vectors, the character
              count is zero (0), followed by exactly one space before
              the newline.

       gremlin was designed for AED terminals, and its coordinates
       reflect the AED coordinate space.  For vertical pictures, x-
       values range 116 to 511, and y-values from 0 to 483.  For
       horizontal pictures, x-values range from 0 to 511, and y-values
       from 0 to 367.  Although you needn't absolutely stick to this
       range, you'll get better results if you at least stay in this
       vicinity.  Also, point lists are terminated by a point of (-1,
       -1), so you shouldn't ever use negative coordinates.  gremlin
       writes out coordinates using the printf(3) format “%f1.2”; it's
       probably a good idea to use the same format if you want to modify
       the grn code.

   Sun/X11 coordinates
       There is no 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

Options         top

       -? and --help display a usage message, while -v and --version
       show version information; all exit afterward.

       -T dev Prepare device output using output driver dev.  The
              default is ps.  See groff(1) for a list of valid devices.

       -M dir Prepend dir to the search path for gremlin files.  The
              default search path is the current directory, the home
              directory, /usr/local/lib/groff/site-tmac, /usr/local/
              share/groff/site-tmac, and /usr/local/share/groff/1.23.0/
              tmac, in that order.

       -F dir Search dir for subdirectories devname (name is the name of
              the output driver) for the DESC file before the default
              font directories /usr/local/share/groff/site-font, /usr/
              local/share/groff/1.23.0/font, and /usr/lib/font.

       -C     Recognize .GS and .GE (and .GF) even when followed by a
              character other than space or newline.

Files         top

              device description file for output driver name

Authors         top

       David Slattengren and Barry Roitblat wrote the original Berkeley
       grn.  Daniel Senderowicz and Werner Lemberg modified it for

See also         top

       gremlin(1), groff(1), pic(1), ideal(1)

COLOPHON         top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, see ⟨⟩.
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2021-08-27.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-08-23.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

groff 1.23.0.rc1.1101-d1263-di2r0tyAugust 2021                       grn(1)

Pages that refer to this page: groff_filenames(5)