HP OpenVMS DCL Dictionary

SHOW DISPLAY

Indicates the node where output from a DECwindows application will be displayed.

Format

SHOW DISPLAY [display-device]

Parameter

display-device
Refers to the display-device parameter specified with the SET DISPLAY command. If you are directing application output to multiple workstations in the same session, you can use logical names to point to each workstation. Using the SHOW DISPLAY command, you can specify this logical name as the display-device parameter to see where application output will be displayed.
If you do not specify a display-device string, the logical name DECW$DISPLAY is used.

Description

DECwindows gives you the ability to run applications across a network. The SET DISPLAY command enables you to direct the output of client applications across the network to an alternate workstation (X display server) for viewing. For example, the SET DISPLAY command allows you to:

Redirect the output from local client applications to a remote workstation for display.
Redirect the output from remote client applications to your local workstation for display. Although the application runs on another processor, it looks the same as any other application running locally on your workstation.

By running applications on a remote processor for local display on your workstation, you can take advantage of larger computers that might be better suited to a specific computing task. By default, applications running on your workstation are displayed on your workstation.
You use the SET DISPLAY command to direct the output from applications to other workstations. The SHOW DISPLAY command lets you see where the output from these applications will be displayed.
Sample output from the SHOW DISPLAY command looks like the following:
Device: WSA2: [super] Node: 0 Transport: LOCAL Server: 0 Screen: 0
The description of each item follows:

Device is your workstation device. A new WSAn device is created each time you use the SET DISPLAY/CREATE command.
Node is the network system on which the output from applications is displayed. When you are running and displaying applications on your node, Node is 0, which is the standard shorthand notation for representing your node.
Transport refers to the mechanism, for example, DECNET or LOCAL, that passes information between the application---the client---and the server. The server sends input from the user to the application and output from the application to the display.
Server is 0.
Screen is 0.

On DECwindows workstations, the Session Manager creates a default workstation device for use by DECwindows processes (like DECterm). When you use the SET HOST command to connect to a remote node, no workstation device is created for that process and DECW$DISPLAY is not defined. You must specifically create new display devices with the SET DISPLAY/CREATE command.
If no definition for DECW$DISPLAY exists, entering the SHOW DISPLAY command returns an error.
Qualifiers to the SHOW DISPLAY command enable you to display properties related to the display device and extract authorization information, as described in the following sections.
Displaying Named Properties (Alpha/Integrity servers Only)

Named property values are designed to store configuration information associated with the display device, such as the network address of a session manager. By using the /ALL and /SYMBOLS qualifiers, you can display all the named properties related to the display device and use them to define one or more global symbols.
See the description of the SET DISPLAY command for more information.
Extracting Authorization Information (Alpha/Integrity servers Only)

If the display device is connected to a workstation that is using either Magic Cookie or Kerberos access control, you can use the /EXTRACT qualifier to obtain authorization information related to the display device from the current X authority file.
See the description of the SET DISPLAY command for more information.

Qualifiers

/ALL (Alpha/Integrity servers only)
Displays all named properties and their values related to the current display device.
/EXTRACT (Alpha/Integrity servers only)
Obtains the authorization data for the display device and writes that data to SYS$OUTPUT. The authorization data is obtained from the current X authority file and is in the format expected by the X Authority utility (xauth).
Note that when using an LBX proxy server, the extracted authorization information references the address of the proxy server and not the X display server.
Do not use the /EXTRACT qualifier with any other SHOW DISPLAY qualifier.
See the description of the SET DISPLAY command for more information.
/QUOTA (Alpha/Integrity servers only)
Displays the current name count and data space quota values for the display device. This display includes the set limit and the amount of space currently available for use.
/SYMBOLS (Alpha/Integrity servers only)
Defines one or more global DCL symbols for each property displayed by the SHOW DISPLAY command. You can then use these property symbols in DCL command procedures.
Each global symbol name follows the form:
DECW$DISPLAY_name
The following are the symbols for predefined properties:
DECW$DISPLAY_NODE
DECW$DISPLAY_TRANSPORT
DECW$DISPLAY_SCREEN
DECW$DISPLAY_SERVER
DECW$DISPLAY_XAUTH

Note that symbols for user-defined properties have a double underscore in the name. For example, the user-defined symbol for the value DISK$USER:[JONES] would be defined as follows:
$ SHOW SYMBOL DECW$DISPLAY* DECW$DISPLAY_NODE == "101.124.99.119" DECW$DISPLAY_SCREEN == "0" DECW$DISPLAY_SERVER == "0" DECW$DISPLAY_TRANSPORT == "TCPIP" DECW$DISPLAY_XAUTH == "DISK$USER:[SMITH]SERVER1.DECW$XAUTH" DECW$DISPLAY__JONES == "DISK$USER:[JONES]"
If a symbol name or value exceeds or violates any DCL limits or naming conventions, the symbol is not set and an error message is displayed.
If the display device uses a proxy server, the symbols DECW$DISPLAY_NODE, DECW$DISPLAY_TRANSPORT, and DECW$DISPLAY_SERVER reflect values associated with the proxy server and not the X display server.
/VALUES=(property-name[,...]) (Alpha/Integrity servers only)
Displays the value for the specified property. If the value consists of one or more items, they are displayed as a comma-delimited list.

Examples

#1
$ SHOW DISPLAY Device: WSA1: [super] Node: 0 Transport: LOCAL Server: 0 Screen: 0 $ SET DISPLAY/CREATE/NODE=ZEPHYR $ SHOW DISPLAY Device: WSA2: [super] Node: ZEPHYR Transport: DECNET Server: 0 Screen: 0 $ SPAWN/NOWAIT/INPUT=NL: RUN SYS$SYSTEM:DECW$CLOCK

$ SHOW DISPLAY
  Device:     WSA1:  [super] 
  Node:       0
  Transport:  LOCAL
  Server:     0
  Screen:     0
 
$ SET DISPLAY/CREATE/NODE=ZEPHYR
$ SHOW DISPLAY
  Device:     WSA2:  [super] 
  Node:       ZEPHYR
  Transport:  DECNET
  Server:     0
  Screen:     0
$ SPAWN/NOWAIT/INPUT=NL: RUN SYS$SYSTEM:DECW$CLOCK

In this example, you are logged in to your workstation, here referred to as node 0. (0 is the standard shorthand notation for representing your node.) You want to run the DECwindows Clock on your workstation and display it on another node, ZEPHYR.
Assuming you are authorized to display applications on ZEPHYR, you redirect the application's output to ZEPHYR with the SET DISPLAY command and enter the SHOW DISPLAY command to verify the location of the redirected display. You then run Clock. Note that a new workstation display device, WSA2, is created when you enter the SET DISPLAY/CREATE command.

#2
$ SET DISPLAY/CREATE/VALUE=(NAME=DECW$SESSION_MANAGER,- _$ SET="tcpip/zephyr:9510") $ SHOW DISPLAY/SYMBOLS/ALL Device: WSA23: [super] Node: 0 Transport: DECNET Server: 0 Screen: 0 User-defined values: "DECW$SESSION_MANAGER" = "tcpip/zephyr:9510" $ SHOW SYMBOL DECW$DISPLAY__DECW$SESSION_MANAGER DECW$DISPLAY__DECW$SESSION_MANAGER == "tcpip/zephyr:9510"

$ SET DISPLAY/CREATE/VALUE=(NAME=DECW$SESSION_MANAGER,-
_$ SET="tcpip/zephyr:9510")
$ SHOW DISPLAY/SYMBOLS/ALL
    Device:    WSA23:  [super]
    Node:      0
    Transport: DECNET
    Server:    0
    Screen:    0
  User-defined values:
    "DECW$SESSION_MANAGER" = "tcpip/zephyr:9510"
$ SHOW SYMBOL DECW$DISPLAY__DECW$SESSION_MANAGER
  DECW$DISPLAY__DECW$SESSION_MANAGER == "tcpip/zephyr:9510"

In this example, you create a display device, and set the DECW$SESSION_MANAGER property to the network address of a session manager on remote node ZEPHYR using port number 9510. The SHOW DISPLAY/SYMBOLS command then defines a DCL symbol for the port value.

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