Date of last revision: 10/26/2005

Xwindows-apps help index


Remote X Window Displays

Because of the flexiblity of X Windows, it is possible to have multiple windows on multiple systems and run applications on more powerful machines from less powerful machines without actually having to sit at that powerful machine. However, in order to take advantage of this, you need to set up your environment properly so that you can fully utilize X Windows.

On windows that are remotely logged into other systems, you need to set up the DISPLAY environment variable so that X Window applications that you excute on a remote system will display on your terminal. You also need to allow the systems you are logged into to have access to your system by using "xhost" to allow remote systems to display windows on your local system.

For example, you are sitting on linux60501 and remotely log into nova4. You need to set the DISPLAY variable on nova4, so that any X Window applcation that you execute while logged into nova4 will display on linux60501. In the terminal logged in to nova4, you type:

DISPLAY=linux60501:0.0
export DISPLAY

in Bourne Again (bash) or Korn (ksh) shell (if you don't know which shell you're in, you're probably in bash) or:

setenv DISPLAY linux60501:0.0

in C (csh) and Turbo C (tcsh) shell. This will redirect any X Window applications that you execute on nova4 to linux60501 so that you can see and use them.

You also have to allow nova4 to have permission to access the X server of linux60501 to display X Windows back to linux60501. If you type:

xhost nova4

in a shell local to linux60501, it will allow nova4 to display X Windows on linux60501. If you type:

xhost +

it will allow any system in the entire Internet to display windows on your screen. Because of this, using "xhost +" is not recommended. People sometimes bring up windows on other people's screen as a prank (i.e., someone might throw up a window containing a particularly nasty picture), and will also be able to see/capture everything you type. If you type "xhost -," it will allow no other systems (except the local machine) to display X Windows on your machine.

To summarize, in the window that is remotely logged into another machine, you need to set the DISPLAY environment variable as shown above (substitute linux60501 with the system you're currently sitting at. On the local machine, you need to type "xhost remote_machine_name" to allow that machine access to your terminal.


Xterm Terminal Windows for Vt100 terminal emulation

( and talking to the SCUACC machine )

There are TWO types of terminal windows that can be brought up in either the HP Vue window system or the Motif Window system. These are "hpterm" and "xterm". If you are in either Window system, you can invoke either terminal type by typing either "hpterm" or "xterm". A new terminal window of THAT type will appear on the screen ( see helpme xwindows-mwm for information on how to simply change to a Motif Window environment ). When a "xterm" terminal is brought up, its terminal emulation type by default is a VT100 terminal type. If you are going to "telnet" or "rlogin" to the Academic Computing Center system (scuacc), then you will need to be in a "xterm" window. This is needed if you want such things as editors to work correctly.

Useful X Windows applications

Here are some other useful X Window applications that users might find useful. man pages are available on each program. These applications and others are located in /usr/bin/X11.
hpterm		Brings up a stanard HP terminal.

xclock		Displays the time in a window similar to an analogue
		clock.

xload		Displays a graphical representation of the load on
		the current system.

xterm		Brings up a vt100-compatible terminal. Useful for
		logging into SCUACC or other systems that require
		vt100.
Programmers will find the programming manuals for X Windows accessable online via "lrom." Check "helpme lrom" for more information.
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