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Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here


d.mon - Controls graphics display monitors from the command line.


display, graphics, monitors


d.mon --help
d.mon [-lpcgsrtux] [start=string] [stop=string] [select=string] [width=value] [height=value] [resolution=value] [bgcolor=name] [output=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


List running monitors and exit
Print name of currently selected monitor and exit
Print commands for currently selected monitor and exit
Print path to support files of currently selected monitor and exit
Do not automatically select when starting
Release and stop currently selected monitor and exit
Disable true colors
Open output file in update mode
Requires --overwrite flag
Launch light-weight wx monitor without toolbars and statusbar
Requires 'start=wx0-7'
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


Name of monitor to start
Options: wx0, wx1, wx2, wx3, wx4, wx5, wx6, wx7, png, ps, html, cairo
Name of monitor to stop
Options: wx0, wx1, wx2, wx3, wx4, wx5, wx6, wx7, png, ps, html, cairo
Name of monitor to select
Options: wx0, wx1, wx2, wx3, wx4, wx5, wx6, wx7, png, ps, html, cairo
Width for display monitor if not set by GRASS_RENDER_WIDTH
Default value: 720
Height for display monitor if not set by GRASS_RENDER_HEIGHT
Default value: 480
Dimensions of display monitor versus current size
Example: resolution=2 enlarge display monitor twice to 1280x960
Background color
Either a standard color name, R:G:B triplet, or "none"
Default: white
Name for output file (when starting new monitor)
Ignored for 'wx' monitors

Table of contents


d.mon allows the user to start, select, list, release, and stop available graphics monitors.

Starting a monitor

In order to display on-screen GRASS graphics, the user must start and select a graphics monitor. By default, the start command actually runs two commands, to both start and select whatever monitor is named by the user. The user can get a list of running monitors by setting the -l flag on the command line. Note that some monitor drivers use environment variables or the specific driver documentation.

When a monitor is started, it is therefore also (automatically) selected for output, unless the -s flag is set by the user; the user can also explicitly select a monitor that has been started.

The desired monitor should be started once and need not be restarted unless it is stopped for some reason. A monitor may continue to run for any length of time, even when no GRASS session is being run.

Stopping a monitor

A graphics monitor has two different types of status: monitor program not running, and monitor running. A monitor that has been started and/or selected will be listed as running; a monitor that has been stopped (or not started) will be listed as not running. The -l flag will list all currently running monitors.

Selecting a monitor

When the user starts a monitor, it is also (automatically) selected for graphics output unless the user sets the -s flag. In order to use (direct graphics output to) a monitor, the user must select that monitor for use, either by simply starting the monitor without the -s flag or by explicitly selecting the monitor for output. Only running monitors can be selected for graphics output.

The user can run multiple graphics monitors by simply starting each of the graphics monitors the user wishes to direct output to.

Releasing (unselecting) a monitor

Currently selected a monitor can be released by -r flag.


d.mon is designed for interactive use. If non-interactive use is needed (e.g., in a script) set GRASS_RENDER_IMMEDIATE=png (or =cairo) and use the related environment variables to control output size etc.


wx0 monitor

To start the interactive wxGUI map display, run
d.mon start=wx0
Blank wx0 display
Figure: The initialization of display monitor wx0
All subsequently displayed data will be rendered on monitor wx0.
g.region raster=elevation -p
d.rast map=elevation
Display wx0 with raster map
Figure: The display wx0 showing an elevation raster map

CAIRO file renderer monitor

A CAIRO monitor can be started (and selected) by
d.mon start=cairo output=out.pdf
From this moment on all displayed data will be rendered into file output.pdf.

List running monitors

To list the currently running monitors, use
d.mon -l

List of running monitors:

Show currently selected monitor

To identify the currently selected monitor, use
d.mon -p


Switching between monitors

To switch back to interactive display mode, here to an earlier started and still running wxGUI monitor, use
d.mon select=wx0

Stopping a monitor

To close the wxGUI monitor, run
d.mon stop=wx0


d.erase, d.redraw, d.rast, d.vect, d.frame

See also list of variables for rendering, display drivers


Martin Landa, OSGeoREL, Czech Technical University in Prague, Czech Republic

Last changed: $Date: 2017-12-13 00:39:11 -0800 (Wed, 13 Dec 2017) $


Available at: d.mon source code (history)

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.4, available here.
Updated manual page: here

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