## DESCRIPTION

d.mon allows the user to start, select, list, query the status of, release control of, stop, and unlock control of, available graphics monitors. The user can run this program either interactively (through a series of menus), or non-interactively by typing the name of the monitor to start, stop, select, or unlock, and any desired flags on the command line.

These parameters perform the following functions:

1. Start 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 available monitors by setting the -l or -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 explictly select a monitor that has been started (see (3) below). After a monitor is started, a blank graphics frame should appear on whatever terminal the user is using to display graphics.

   The desired monitor should be started once and need not be restarted unless it is stopped (option 2) for some reason. A monitor may continue to run for any length of time, even when no GRASS session is being run. The monitor program runs in the background.

2. Stop a Monitor.
   Sometimes the monitor program needs to be stopped (terminated). Choosing option 2 will terminate a user-specified monitor program. 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 (list status) flag will list the status of each monitor connected to the system.

3. Select 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 explictly selecting the monitor for output using option 3. Only running monitors can be selected for graphics output. Once the user has selected a monitor for output, no other user can use this monitor for graphics output until the monitor driver is either released (by the user) or unlocked (by any user on the system).

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

4. Release a Monitor.
   Once a user has selected a monitor for graphics output, it is locked for use by that user until either: (1) the user voluntarily releases control of the monitor for use by another (option 4), or (2) another GRASS user unlocks the user's control of the monitor. Menu option 4 appears only to the person who has selected the monitor (since only that user can release control of his selected graphics monitor.) If another user wishes to unlock the user's control of the monitor, that user must run d.mon from the command line and set the unlock=name parameter.

You may choose multiple options within the d.mon program.

## NOTES

The d.mon program can regulate control of graphics monitors both in systems using multiple monitors and in systems using a single graphics monitor.

## SEE ALSO

d.erase
PNG driver
Xdriver
variables list

## AUTHOR

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory,
Full 24bit support by Roberto Flor, ITC-Irst, Trento, Italy
Code cleanup by Glynn Clements

Last changed: $Date: 2005/01/19 11:05:52 $