Workbook for SLD Offline Users - Setting Display

There are two common problems in creating Xwindows displays. One involves the set display command, the other involves security.

Set Display

When you issue an command that tries to open a new Xwindow, such as web or mxrn, the system needs to know what node to display the file on (a "node," in this case, is an individual workstation). In many cases the system can figure this out for itself, but in some cases, such as when you have issued a set host command, the system needs help.

To see if the system already knows the correct node for display, issue the command show display.

A typical response might be:

    Device:    WSA5:  [user]
    Node:      SLDX99.SLAC.Stanford.EDU
    Transport: TCPIP
    Server:    0
    Screen:    0

If instead you get a response like:

   %DECW-W-OPENIN, error opening DECW$DISPLAY as input
   -SYSTEM-W-NOSUCHDEV, no such device available

the system does not know what node to use for display.

To tell the system what node to use for the display, issue the command

   set display/create/node=your_node_id

For example,

   set display/create/node=sldx99

Security

Most workstations are set up to only allow display to come from a specific list of users on a specific list of hosts.

For example, a workstation may be set up to only allow displays from user PERL on host SLACVX and user PERL on host SLD. No other combinations of user and host would be allowed to display to this workstation.

This security feature may get in your way when you issue some commands that try to create new Xwindows.

If you get a message telling you that the system has refused to create a connection, check your security options.

If you are running a VMS session manager, look in the Security dialog box in the Session Manager's Options menu. Specify the host node and username and then hit the Apply or OK buttons.
If you are running a Unix session manager, use the xhost + command followed by the name of the host node.

Joseph Perl
17 February 1995