From the user's perspective, every X server has a display name of the form:
hostname:displaynumber.screennumber
This information is used by the application to determine how it should connect to the server and which screen it should use by default (on displays with multiple monitors):
hostname
The hostname specifies the name of the machine to which the display is physically connected. If the hostname is not given, the most efficient way of communicating to a server on the same machine will be used.
displaynumber
The phrase "display" is usually used to refer to the collection of monitors that share a common keyboard and pointer (mouse, tablet, etc.). Most workstations tend to only have one keyboard, and therefore, only one display. Larger,
screennumber
Some displays share a single keyboard and pointer among two or more monitors. Since each monitor has its own set of windows, each screen is assigned a screen number (beginning at 0) when the X server for that display is started. If the screen number is not given, then screen 0 will be used.
On POSIX systems, the default display name is stored in your DISPLAY environment variable. This variable is set automatically by the xterm terminal emulator. However, when you log into another machine on a network, you'll need to set DISPLAY by hand to point to your display. For example,
% setenv DISPLAY myws:0 (C Shell)
$ DISPLAY=myws:0; export DISPLAY (Korn Shell)
The xon script can be used to start an X program on a remote machine; it automatically sets the DISPLAY variable correctly.
Finally, most X programs accept a command line option of
$ xload
X servers listen for connections on a variety of different communications channels (network byte streams, shared memory, etc.). Since there can be more than one way of contacting a given server, the
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