Programs running under the X Window System organize their user options under a hierarchy of classes and resources. You can specify default values for these options in your X resource file, usually named ~/.Xdefaults or ~/.Xresources. Changes in this file do not take effect immediately, because the X server stores its own list of resources; to update it, use the command xrdb—for instance, xrdb ~/.Xdefaults. Settings specified via X resources in general override the equivalent settings in Emacs init files (Init File), in particular for parameters of the initial frame (Frame Parameters). (MS-Windows systems do not support X resource files; on such systems, Emacs looks for X resources in the Windows Registry, first under the key HKEY_CURRENT_USER\SOFTWARE\GNU\Emacs, which affects only the current user and override the system-wide settings, and then under the key HKEY_LOCAL_MACHINE\SOFTWARE\GNU\Emacs, which affects all users of the system. The menu and scroll bars are native widgets on MS-Windows, so they are only customizable via the system-wide settings in the Display Control Panel. You can also set resources using the -xrm command line option, as explained below.) Each line in the X resource file specifies a value for one option or for a collection of related options. The order in which the lines appear in the file does not matter. Each resource specification consists of a program name and a resource name. Case distinctions are significant in each of these names. Here is an example:

emacs.cursorColor: dark green

The program name is the name of the executable file to which the resource applies. For Emacs, this is normally emacs. To specify a definition that applies to all instances of Emacs, regardless of the name of the Emacs executable, use Emacs. The resource name is the name of a program setting. For instance, Emacs recognizes a cursorColor resource that controls the color of the text cursor. Resources are grouped into named classes. For instance, the Foreground class contains the cursorColor, foreground and pointerColor resources (Table of Resources). Instead of using a resource name, you can use a class name to specify the default value for all resources in that class, like this:

emacs.Foreground: dark green

Emacs does not process X resources at all if you set the variable inhibit-x-resources to a non-nil value. If you invoke Emacs with the -Q (or --quick) command-line option, inhibit-x-resources is automatically set to t (Initial Options). In addition, you can use the following command-line options to override the X resources file:

-name name, –name=/name/

@opindex –name This option sets the program name of the initial Emacs frame to name. It also sets the title of the initial frame to name. This option does not affect subsequent frames. If you don't specify this option, the default is to use the Emacs executable's name as the program name. For consistency, -name also specifies the name to use for other resource values that do not belong to any particular frame. The resources that name Emacs invocations also belong to a class, named Emacs. If you write Emacs instead of emacs, the resource applies to all frames in all Emacs jobs, regardless of frame titles and regardless of the name of the executable file.

-xrm resource-value, –xrm=/resource-value/

@opindex –xrm This option specifies X resource values for the present Emacs job. resource-value should have the same format that you would use inside a file of X resources. Several -xrm options are possible to include multiple resource specifications. You can also use #include "/filename/" as resource-value to include a file full of resource specifications. Resource values specified with -xrm take precedence over all other resource specifications.