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Environment Variables

Environment Variables

uDraw(Graph) supports the environment variables listed below.

Notes for the Windows® platform:

Instead of using environment variables you can set corresponding variables of type "zero terminated string" in the following paths of the registry. The variables are searched in both paths in this order:


After you have installed uDraw(Graph) with the self extracting installer, the values for the variables $UDG_HOME, $UDG_ICONDIR and $UDG_LANG are automatically determined from your current environment and are automatically inserted into or overwritten in the Windows® registry. The automatic installer uses the following registry keys:


If you do not have the permissions to modify HKEY_LOCAL_MACHINE entries in the registry (i.e. no administration rights), then the alternative root HKEY_CURRENT_USER is used instead. The registry entries have the same semantics as described for the variables described below. uDraw(Graph) will use them if it cannot find the environment variable as a fallback and there is no need to set the environment variables any more. If the registry is set at both locations (HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER), uDraw(Graph) will use only HKEY_CURRENT_USER.


This is the only mandatory environment variable that must be set to be able to start uDraw(Graph). This variable is automatically set by the uDraw(Graph) installation on Windows® and when you use the *.rpm distribution on LINUX®. This environment variable specifies the directory where the uDraw(Graph) distribution is located on your computer, i.e. the absolute file name of the topmost directory "uDrawGraph-3.1.X" (where X is the actual minor release number).

Note: Be careful with moving the uDraw(Graph) distribution to another location on a filesystem shared by many users. You can do so (by setting $UDG_HOME to the new location), but other users may have problems accessing the help system afterwards. The reason is that the current location of the online documentation is stored when using menu Options/Save, so for these users the system will always look at the former location. The current setting can be seen and modified with menu Options/General Settings. So if you have to move the distribution, make sure that all users are updating their options or leave a link (or alias) at the former location.


This environment variable is used to specify the directories where the system will look for files containing images in the ".gif", ".xbm", ".xpm" or ".bmp" graphic format. Images can be used to visualize particular nodes of a graph (see node attribute IMAGE and for the icon bar which can be extended by application specific icons with API command app_menu(create_icons(...)). uDraw(Graph) will look for icons in the default "icons" directory of the distribution, before going on in the directories specified with this variable. The individual directories must be separated with ":" on UNIX® and LINUX® and with ";" on Windows®.


This variable is used to set the text of the user interface to another language. If unset, value "C" is supposed which is the English user interface. A German user interface can be used with value "de". Other languages may be provided by the user, see chapter internationalization for more information. The variable is used to select one of the translation files located in directory "lib/uDrawGraph/" of the uDraw(Graph) distribution. A translation file begins with "uDrawGraph_" and ends with ".lang".


By default, uDraw(Graph) will look for the graph editor application in directory $UDG_HOME/bin/grapheditor, if started with option -graphedit. To let the system look for the editor at another location you can set this environment variable to a different directory.

$HOME and $TMP

Sometimes uDraw(Graph) has to create temporary files. If the environment variable $TMP is set, its value is used as the directory for temporary files. Otherwise the environment variable $HOME is used. If neither $TMP nor $HOME is set, the current working directory is used.