add new users that can login via X-windows

[true1ever]

So as I was playing around on the thinclient PC, I got the idea that it would be nice to be able to save the settings of each user so they can be restored next time, kind of like a persistent home for all the new created users. Apparently this is pretty simple to implement.
Here is a script to save all the password settings and the contents of all new user's home directories, let's call it save_tcph:

#!/bin/bash
tar -cvvf /home/knoppix/tcph.tar /home/* /etc/passwd /etc/shadow /etc/group /etc/gshadow --exclude /home/knoppix
gzip /home/knoppix/tcph.tar

Once all your X-terminals are logged out, on the server you can run save_tcph and it will create a file called tcph.tar.gz in the knoppix home directory. At this point, you can run the regular "Save knoppix configuration" to save the knoppix user's settings to whichever media you prefer. Since the tcph.tar.gz file is in the knoppix directory, you are also tranparently saving all the other user's settings and all the passwords you created when you set up the new users.

Next time you boot up when you are ready to resume the X-terminal sessions, use the regular script in the previous post that enables thinclients but don't add any users. Then all you need to do is run the following script, let's call it restore_tcph:

!#/bin/bash
cd /
tar xfvz /home/knoppix/tcph.tar.gz

All your users that you previously created are instantly there again and you are able to log from any X-terminal as any user and see that user's desktop, along with any files they had in their home directory and any settings are exactly as they were when they logged out.

How about that?

regards,
Jim

[true1ever]

BTW, in case you were wondering, tcph is just an acronym for thin client persistent home in case you were wondering how I came up with the file names

[A. Jorge Garcia]

I was just reading the Desktop articles by Michael C. Barnes on desktoplinux.com. He mentions that the latest version of KNOPPIX includes LTSP for thin clients booting off a server. How does this work? Is this different from the solutions you all are advancing here in this thread?

TIA,

[true1ever]

I think that article has some of their facts incorrect. AFAIK knoppix does not include LTSP, he may have mistakenly thought that the knoppix terminal server function is thin-client.

regards,
Jim

[true1ever]

By the way, I discovered a bonus function when using the above scripts, any password that you may have set for root or the knoppix user carries accross re-boots so you don't need to set it again

P.S. This post typed from a Pentium200 w/ 32 MB RAM thin client, and it performs surprisingly fast

[RockMumbles]

From my experiences the difference between running X-terminals and remote-terminal sessions is:

When running X-terminals logged into a server, especially if you are not running a local X-session on your server, the server resources are used for running the OS, desktop environment or window manager, applications, and the sever part of the X-window system. Your X-terminals are running the OS and the display interface (X-window system client). So each part of the system has it's own task, and the only network data transmission is information regarding the X display.

When running something like LTSP or knoppix remote-terminal sessions the thin-client is actually running the OS, you are booting from a remote computer but running on the local system. If you are running PXE or LTSP thin-clients, applications are loaded from the server's hard drive or cd, also your swap is on the remote computer as most thin-client do not have a hard drive at all, this is a whole bunch more network activity that running X-terminals and requires that all computers have capable enough hardware to run the full linux system.

A 16mb 486DX with a capable video card can function as an X-term (maybe not a great one but it will function), the same computer cannot login to a knoppix remote-terminal session or LTSP server and run X, it does not have the resources to run a 'complete' linux system, the OS, X, desktop environment or window manager and applications.

HTH

rock

[true1ever]

Another way to explain it, when you are using knoppix terminal server, you are basically just connecting the cdrom of the server to your local PC via the network. All applications still load and execute locally at the speed of the local CPU and the memory requirements are the same as running from CD. Your home directory is on the local ramdisk. If you reboot unexpectedly you will lose files and settings in your home directory.

When running thin-client mode, you are running the applications on the server. Applications load and execute at the speed of the server's CPU. (There is some overhead for the screen rendering and network transmission but it's not too significant for most applications except for some games or video intensive applications). Since the local machine only needs to draw the screens received from the server and send mouse and keystrokes to the server, the requirements on memory and CPU speed is much, much less than the other option. You don't need to have local swap either. The home directory is on located on the server If you reboot, you will not lose any files saved in your home directory since they are stored on the server.

[A. Jorge Garcia]

In other words, using the thin client model, a user could login to the remote server and save work there under their login name in a remote /home, right? BTW, I'm assuming an hdd install for the server and CD boot for the clients.

This would not tax the resources of the client PC, however, you'd need a lot of resources on the server if you have more than a few concurrent users, no?

If so, I think I can try the thin client approach in my new lab next year. I'm confused as to setting that up. What has been discussed above relates to XTerm (taxing to the client) instead.

TIA,

[RockMumbles]

When I use the term X-terminal I am talking about running a (small) local OS on a machine that basically has a base linux system, networking and X. It is NOT booting off of a remote computer it is running as a terminal that is running X (therefore the name X-terminal) that is operating only as a display device. With X-terminals all applications and storage are on your server, which I like to call the application server.

When true1ever uses the term thin-client he is talking about the same thing as I am, in linux or unix terms what we are doing is generally called running X-terminals. I think that the term thin-client can actually be used in both an X-terminal system and also a LTSP or knoppix terminal-session for the terminal device.

The difference is X-terminals are functioning as display devices attached to a remote computer, the application server.

With remote booting LTSP or knoppix terminal-server, the terminals are more than just a terminal, they are running the full linux operating system (which is on the server), they are not just display devices, they have to be capable of running the entire OS.

A.J.G. I've gone through this before with you about hardware, it depends on how many users and what you are doing. A 1GB machine with 512MB of ram and a large swap partition 256 or larger on a fast network should easily support 12 or so users depending on what you are doing, you'll have to experiment. A friend's business which uses star-office for microsoft office docs, netscape, etc. runs at least 6 users and is running off of a 200Mhz machine with 160MB of ram.

In an hour you could set up one of your existing labs with knoppix runnning entirely from cd doing what we are discussing here. Try it and see how it works, that would be the best thing for you to do at this point. Then realize that with a hd install it would be faster.

rock

[true1ever]

Typically in the windoze world, the O/S and software is programmed to always expect the CPU, display, keyboard and mouse, swap file, etc to be on the same machine.

In X-windows the process is more modular, the display doesn't necessarily have to be on the machine that is running the process. Basically you have the Xserver which typically runs on the client machine (yeah, I know it's a little confusing but the Xserver software is what allows you to view the GUI), then you have the windows manager (kde, icewm, gnome, etc) which can run on the same or a remote machine, and then the client applications which get their input and output through the Xserver.