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This chapter is from the book

Managing Your Edubuntu Clients

Although you will not be installing anything on your clients, it is important to realize that there are still some maintenance tasks specifically directed toward the clients.

Updating the Client NFS Root

You may have an up-to-date server, but this does not necessarily mean that the system the clients run on is up to date. Remember that essentially you have two versions of Ubuntu installed on the Edubuntu server. One is the server and another is a very slimmed down version that simply provides clients with enough capability to be able to boot and log in.

First, open a terminal window using the Applications > Accessories > Terminal link in the main menu. You need to copy your list of package sources from the server to the client. To do this, type the following line into the terminal window, press Enter, and type your password when prompted.

sudo cp /etc/apt/sources.list /opt/ltsp/i386/etc/apt/

Your root directory must be altered so that you are inside the NFS client root. That way, when you enter commands, they will be run on the client system and not on the main server. To do this, issue the commands shown here. The first makes sure that all programs running inside the chroot will work as expected.

sudo chroot /opt/ltsp/i386
mount -t proc proc /proc

Although you copied the list of package sources from the server to the client, you’ll need to update the actual list of packages available to be installed or upgraded. To do this, you must issue the following command, which will download the latest list of packages from the Internet.

apt-get update

Once this has completed, it is time to start the upgrade. To do this, enter one final command:

apt-get upgrade

This will show you a list of all packages that need to be upgraded and will prompt you to continue. If you are happy with the selection, press y to confirm and to begin the installation process. When the installation is completed, you’ll need to reboot the client machines for the changes to take effect.

Important: Don’t forget to unmount the proc in the chroot by typing sudo umount /proc and pressing Enter, and then leave the chroot by pressing Ctrl-D.

Upgrading the Client’s Kernel Version

Once in a blue moon, or if a security update is available, it is necessary to upgrade the kernel version of the client machine. This process should be treated with caution and should really be performed only if you are experiencing problems with your client’s hardware. To upgrade the kernel version in the client NFS root, you must explicitly tell it to install the new kernel. Much like in the upgrading of the client root software described in the previous section, you must first load a terminal and enter the client chroot, using this command:

sudo chroot /opt/ltsp/i386
mount -t proc proc /proc

Once here, update the latest version of the packages using the following command:

apt-get update

If you know there is a newer kernel available and you know the package name, the next step is easy. If you don’t know whether there is a new kernel and would like to check, follow these steps.

You first need to find out what kernel image you currently have installed. Issuing the following command will yield an output similar to that seen below. Remember that you must be in the chroot to run these commands; otherwise you’ll just be looking at the kernel versions of the main server and not the client’s chroot.

root@ubunt:~$ dpkg -l | grep linux-image
ii  linux-image-2.6.24-12-generic             2.6.24-12.22
  Linux kernel image for version 2.6.24 on x86
ii  linux-image-generic                      2.6.24.12
  Generic Linux kernel image
root@ubunt:~$

From here we can see that the latest version of the Linux kernel image is 2.6.24-12.22. Running the following command shows what the latest version of the kernel is currently in the repositories. Again, remember that you should be in the chroot when issuing this command.

root@ubunt:~$ apt-cache show linux-image-2.6.24-12-generic | grep Version
Version: 2.6.24-12.22
root@ubunt:~$

Notice how the package name from the previous output of code, linux-image-2.6.24-12-generic, is now used again in the second command to find the latest version of the currently installed kernel. In this example, the two kernel versions are the same. However, if they differed, using the following command would update the kernel version in the chroot environment.

apt-get install linux-image-2.6.24-12-generic

Once the kernel has been upgraded, you must then run the LTSP script for updating the chroot with the correct information that allows the new kernel to be used in preference to the old one. To do this, first unmount proc, as shown before, and then exit the chroot by pressing Ctrl-D. Then run the following command:

ltsp-update-kernels

After the script has finished, you should reboot your clients’ machines to have them start using the new kernel.

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