Environment Variables

Several environment variables are used by VMD to determine the location of certain files and directories. These variables are accessible to text interface through array env. These variables include:

• DISPLAY : (Unix-only) The X-Windows display that VMD should use for displaying the VMD forms and menus, as well as the graphics window. If this environment variable is not overridden by VMDGDISPLAY all VMD windows will be directed to this display.

• VMDDIR : The directory which contains the VMD data files (such as this help file) and architecture-specific executables. By default, this is /usr/local/lib/vmd on Unix systems, and C:\Program Files\University of Illinois\VMD on Windows sytems.

• VMDTMPDIR : The directory which VMD should use for temporary data files. By default, this is /tmp, or /usr/tmp on Unix systems, and C:\ on Windows.

• VMDBABELBIN : The complete path and filename for the program babel, which is used by VMD to convert molecular structure/coordinates files into PDB files which VMD can actually understand. If this is not set explicitly, the VMD startup script will attempt to find babel in the current path. If Babel cannot be found or is not installed, VMD will not be able to read molecular file formats other than PDB, PSF, and binary DCD files.

• VMDFILECHOOSER : Specifies which file chooser to use for loading and saving files from the GUI. At present, this should be either FLTK, which uses Fltk's platform- independent file chooser, or TK, which uses Tk's file chooser. The Tk file chooser is the default and uses a native Windows interface on Windows platforms. The Fltk file chooser looks the same on all platforms, supports tab completion but not drive letters, and is probably most appropriate for Unix environments. The file chooser can be overridden at any time by changing the environment variable (e.g., in Tcl, set env(VMDFILECHOOSER) FLTK).

• VMDCAVEMEM : (Unix-only) This overrides the default size of the shared memory arena which is allocated by VMD when the CAVE starts up. The variable must be an integer number of megabytes. Since this is the only shared memory pool allocated, and it is done only once, you must choose a value sufficient to account for the largest scene you intend to render in VMD in that CAVE session. The default value unless otherwise specified is 80 Megabytes. Values of 200MB to 512MB are commonly needed for large molecular systems containing several hundred thousand atoms.

• VMDGDISPLAY : (Unix-only) The name of an X-Windows display that VMD will use to display the graphics window. This environment variable is only used on Unix systems. Through the use of the the DISPLAY and VMDGDISPLAY envrironment variables, the VMD graphics window can be placed on a separate screen from the forms and menus. This is particularly useful when giving 3-D demonstrations using a projector. The forms and menus can be kept on a different screen from the graphics so that they do not distract the audience.

• VMDHTMLVIEWER : The name of the HTML viewer (Netscape, Mosaic, whatever you prefer) that VMD should use to display HTML documents (such as this help file). By default, this is Netscape.

• VMDIMAGEVIEWER : The name of the external program to use for displaying VMD snapshots (or other images), in various formats.

• VMDSCRDIST : Distance to the VMD image plane.

• VMDSCRHEIGHT : Height of the VMD image plane.

• VMDSCRPOS : Position of the VMD graphics window (x,y).

• VMDSCRSIZE : Size of the VMD graphics window (x,y).