What are some alternatives?

What are some alternatives?

Ans. A hard link: - is a reference, or pointer, to physical data on a storage volume. On most file systems, all named files are hard links. The name associated with the file is simply a label that refers the operating system to the actual data. As such, more than one name can be associated with the same data. Though called by different names, any changes made will affect the actual data, regardless of how the file is called at a later time. Hard links can only refer to data that exists on the same file system.

Ans. The duties of a system administrator are wide-ranging, and vary widely from one organization to another. Sysadmins are usually charged with installing, supporting, and maintaining servers or other computer systems, and planning for and responding to service outages and other problems. Other duties may include scripting or light programming, project management for systems-related projects, supervising or training computer operators, and being the consultant for computer problems beyond the knowledge of technical support staff. A System Administrator must demonstrate a blend of technical skills and responsibility.

A system administrator's responsibilities might include:

• Performing routine audits of systems and software.

• Performing backups.

• Applying operating system updates, patches, and configuration changes.

• Installing and configuring new hardware and software.

• Adding, removing, or updating user account information, resetting passwords, etc.

• Answering technical queries.

• Responsibility for security.

• Responsibility for documenting the configuration of the system.

• Troubleshooting any reported problems.

• System performance tuning.

• Insuring that the network infrastructure is up and running.

Ans. To build a new kernel follow the following steps;

1. Where to get the kernel source: - When you install Linux, you can specify that you want the kernel source installed. Or you can add the kernel source later from either the Red Hat 9 CD or from rpmfind.

We can download the latest version, see The Linux Kernel Archives at http://www.kernel.org. The latest stable version is listed first. Then download the kernel source archive by clicking on the F (which stands for Full source):

2. Uncompress and extract: - the kernel source into /usr/src on your systemwith the following command:

#cd /usr/src

#bzcat linux-2.4.20.tar.bz2 | tar xvf -

Then create a symbolic link:

#ln -s linux-2.4.20 linux

3. To build a kernel :- If this is the first time you're building a kernel on a Red Hat system, it's easiest if you start with Red Hat's kernel sources and with the kernel configuration template that your system was built with:

# cd /boot

# ls config*

config-2.4.20-8

# cp config-2.4.20-8 /usr/src/linux/.config

Then you can customize your kernel configuration by typing:

#cd /usr/src/linux

#make xconfig

After you are finished customizing the kernel, you can build it: #make dep bzImage modules modules_install

4. After building the kernel : -Copy the resulting kernel to the /boot directory with any name you'd like for it:

#cp /usr/src/linux/arch/i386/boot/bzImage /boot/mynewkernel

If your machine is configured to boot with lilo then edit /etc/lilo.conf, and add a reference to your new kernel. Look at other entries in /etc/lilo.conf to determine what disk shoud be used, etc. Here is a sample of what one might add to /etc/lilo.conf:

image=/boot/mynewkernel

label=mynewlabel

read-only

root=/dev/hda8

Then type:

#lilo

If your machine is configured to boot with grub then modify /boot/grub/menu.lst file.

title Linux 2.4.20 with all my new configuration

root (hd0,1)

kernel /boot/mynewkernel root=/dev/hda2

That is all (you don't need to run a command after modifying the grub configuration file like you would using LILO). When you reboot your machine, you will be able to choose to boot the new kernel.

Q13. Which are the utilities of manual (kernel) module loading, unloading & listing?

Ans. Kernel Module Utilities: - A group of commands for managing kernel modules is

available if the module-init-tools package is installed. Use these commands to determine if a module has been loaded successfully or when trying different modules for a piece of new hardware.

The command /sbin/lsmod displays a list of currently loaded modules Module Size Used by nfs 218437 1

lockd 63977 2 nfs

parport_pc 24705 1

For each line, the first column is the name of the module, the second column is the size of the module, and the third column is the use count. The /sbin/lsmod output is less verbose and easier to read than the output from viewing /proc/modules. To load a kernel module, use the /sbin/modprobe command followed by the kernel module name. By default, modprobe attempts to load the module from the /lib/modules// kernel/drivers/ subdirectories. There is a subdirectory for each type of module, such as the net/ subdirectory for network interface drivers. Some kernel modules have module dependencies, meaning that other modules must be loaded first for it to load. The /sbin/modprobe command checks for these dependencies and loads the module dependencies before loading the specified module.

To unload kernel modules, use the /sbin/rmmod command followed by the module name. The rmmod utility only unloads modules that are not in use and that are not a dependency of other modules in use.