Customizing startup of the Graphical Environment

Using X terminals

You can use X terminals to run Graphical Environment sessions. In fact, you can configure your X terminal so the scologin display manager automatically manages the X terminal's display. When you log in through the scologin window, you start a Graphical Environment session, running on the host machine and displaying on the X terminal.

Many X terminals can use the X Display Manager Control Protocol (XDMCP) to facilitate the connection to remote hosts through scologin. From a user's standpoint, the main advantage of XDMCP is that it allows you to turn an X terminal off and instantly re-establish the connection to the scologin host machine when you turn the X terminal back on. When you turn on an X terminal, scologin automatically displays a login window. The exchange of information between the X terminal and the remote host is invisible to the user. In fact, XDMCP and scologin are intended to make X terminals as easy to use as traditional character terminals. With XDMCP, an X terminal basically requests a connection to a remote host, is recognized by the host, and is sent a login prompt by scologin.

If you are using X terminals at your site, the way you set up scologin depends on whether or not the terminals can communicate through XDMCP. If a terminal cannot communicate using XDMCP, you must include an entry for it in the /usr/lib/X11/scologin/Xservers file and the terminal must be left powered on at all times to maintain the connection to the host machine.

If an X terminal can communicate through the protocol, the machine that will host the scologin process requires no configuration. However, the X terminal must be configured to communicate with the host through the X terminal's setup procedures, which vary from one model to another. Some X terminals let you specify the address of a host machine from which you want to run the display manager. Some X terminals can broadcast a request for a host over the network and then display a list of all available hosts from which the user can choose. Other X terminals can broadcast a request and merely accept the first available host.