Loading External Resource Settings

The Xt intrinsics routine XtVaAppInitialize, amongst other things, loads and merges external resource settings in to the application's resource database, from the following sources, in the following order:

1. Resource settings from a file, with the name of the application's class, maintained in a system-owned, publicly accessible area, are loaded. On UNIX systems, this file usually resides in the directory /usr/lib/X11/app-defaults.
2. Resource settings from a file, with the name of the application's class, maintained by the user, are merged. On UNIX systems, this file is expected to reside in the directory specified by the user's environment variable XAPPLRESDIR, or if that is undefined, in the user's home directory.
3. Resource settings derived from the resource property of the display, as set by the X resource database application xrdb, are merged. If no such property is found, the contents of a file called .Xdefaults, in the user's home directory, is searched.
4. Resource settings derived from a file specified by the user's environment variable XENVIRONMENT, are merged. If this environment is undefined, the contents of a file called .Xdefaults- host is searched, where host is the hostname of the computer on which the application is running.
5. Any resource settings entered on the command line are merged.

In the above list, the files for cases 1 and 2 are specific to the application and are usually created by the application developer. The sources mentioned in case 3 are specific to the display and may contain resource settings for other applications. The sources mentioned in case 4 are specific to the computer on which the application is running, and may contain resource settings for other applications. Case 5 is application specific.