Welcome back friends now in this video we are going to learn about kernel services on our h here. So let's start the Linux kernel is the core of Red Hat Enterprise Linux operating system. It is the kernel responsibility to control hardware and for security allocate resources such as CPU and memory. And kernel is known as core, which is everything centralized on your operating system on a chip. Most of the operating system is not Linux, but rather a collection of applications that make use of facilities provided by the Linux kernel. In particular, the Free Software Foundation or gmu provides a great deal of utilities and core libraries that have made Linux operating system possible.

So the kernel is very important it performs system initialization process scheduling, memory management, security, from se linings to firewall rules and everything. It provides a buffer and catch to stay feed of our hardware access implement standard network protocols and file system format that is being defined by you or your system utilities. And then is kernel is the code. There are multiple kernel images and variants based on different architectures like x86, x86 or 464 bit or 32 bit tight it tinium power Pc 64 s 390 x and so on. But there are three kernel versions available primarily for x86 architecture. It is very popular and normally used within Intel and AMD processors.

One is a regular, where we have one or more processors but four GB of RAM or less the processor one or more processor needed means that have one or two code, single code, double core referral code and so on. But the ram size is to be four GB or less. Then there is another version that is p, where multiple processors and up to 64 GB of RAM is specifically for us servers, where we need multi core processors to speed up the process like Intel Xeon or I seven with 64 GB of RAM. Then we need to install this image on regular regular would be preferred over a desktop and laptop environment. And then is a third image for kernel image that is M which is needed for virtualization virtualization needs a nice or separate code to be implemented. It is separate from the basic kernel of your operating system because it's allow you to do certain tasks that couldn't you could not perform on a single host.

So, there are three images and you should be aware of it. The kernels are always installed under the directory boot VM Linux. There are different kernel modules. Modules are basically small kernel extensions that may be loaded and unloaded at will when you want to load or unload. There are different kinds of modules which fall under the corner. And you can check them out or uncheck anytime you can download a new newer version of modules can provide extra functionality or enhance the performance of kernel.

It can be in Limited as drivers that could be hardware drivers or other drivers, file system, firewall and more. They are located basically under the directory life, liberal library and modules and provide the username, mandatory. It is compiled for a specific kernel version. The modules are basically meant for a specific kernel version they are not generalized. There are different versions and are provided with the kernel RPM, the package management. A third party modules may be added, but they are not referred.

You should be concerned about security. If you are dealing with a server environment, you must be careful by installing third party modules on kernel. You can install a third party tools or utilities on your system, but do not prefer to install third party modules on kernel Then there is a utility called LS mod, which provides a list of loaded modules. There are two different options for LS mod, the mod pro and more info. The mod pro can load and unload modules. mod info displays information about any available module, you can run these commands, or you can find the GR utility from the applications panel of her desktop.

There is a configuration file called mod pro insight, etc directory that could be used for module configuration. You could configure different kinds of parameters, aliases, and commands to execute when a module is loaded or unloaded. You can configure parameters to pass to a module when it is loaded. You can also create aliases to represent a module name. You can access those from Seelye road from lemans terminal or from goi option in the configuration file itself. Then you can manage initial ram disk, which provides modules loaded early in the boot process using the init rd command.

This file is located under boot, image rd. And image name. It provides you an extra module sometimes needed to be added due to falling reserve. When you add a new hardware to the system, for example, SCSI controller, or you may add a new feature such as USB devices. Or you can add modules that need to load automatically at boot time. For this purpose, you need to configure initial ram disk or in it rd You can use a MK init rd or make any rd with a with an option to rebuild an extra module.

Then there comes a accessing drivers through directly Dave which is a directory for a file system. The files under Dave used to access drivers. You can read from and write to those files are valid of operations. Read from serial ports like the command would be for reading a serial port as a cat slash dev slash TTY as zero. for writing a serial port, you can write message in eco and provided to dev TTY s o Three file attributes determine which driver to access device number a major number minor number, these are the attributes that a turbine drivers to access. Then there are two types of devices on Cardinal.

The device mode example to block devices the character devices. The block devices are CD ROM hard is a CI SATA USB storage software raid, that is an implementation of a distribution partition of automatic configuration. This could be find on the following directories, then the collector devices like Virtual Console, software devices, random numbers, and so on. These are the consistent properties of Cardinal that you vices that could be configured with them. You can manage them with Udemy. So Udemy managers file is stored under Dev.

It manages files only created if a corresponding device is plugged in. Suppose you want to configure the pendrive you first need to mount a pendrive then you can consider the files for on pendrive if corresponding devices plugged in. Similarly for SATA hard disks and other devices, the files are automatically removed when device is disconnected. You're devastated statements are under the rules dot domain in UTM EDC data directory, which determines file names, permissions, owners and groups. It also determines the command to execute when a new device shows up. You can also add files under Dave with Command, you have to provide a variables the kernel variable to SDA named USB key, same link he was v storage and so on.

To insert a statement such as you need to create a new file under rules dot d you can create device filenames with album name and is stored at Tim. Next time when the property get plugged in. files can be added manually with MK node command by writing the command as as as the syntax here, MK note Dave, USB device b and a quote from however m keynote is not persistent. It was sometime run or sometime it may not function as you desire. Then there comes a kernel configuration which is very important. You need sometimes you need to configure Colonel according to your users if you are an advanced users, otherwise you don't need basic kernel configuration.

But it can be find on the root directory basically, the proc which is used to set kernel configuration, you can configure virtual file systems you can create your own file systems, the files are not stored on the hard disk. It is virtually there. Then you can create entries that are not persistent a modification get reinitialized after reboot, which is used to display process information memory resources, hardware devices, kernel memory and so on. You can also configuration can be used to modify network and memory subsystems or modify kernel features. The modifications are generally applied immediately after you change the configuration. You don't need to restart yourself Tell the proc Examples include the four read only files write readwrite entries.

So, these are the links where you could go for configuration, the process or directly proc Then comes a persistent kernel configuration that exists for all the side the persistent and non persistent the difference between these two things, non persistent configurations are applicable to only your computer is on if it is restarted or shut down the configuration the in persistent configuration Get lost. And next time when you restart your system if you have configured persistent kernel configuration they exist. They there is a command called sis CTL, which adds persistence To proccess settings, statements added to this configurations, sis CTL configuration automatically get reflected under proc after a reboot. They need rotation you need to reboot restart and it becomes applicable. The configuration is maintained or monitored using sis CTL command which is used to there are certain parameters. For example, if you want to list all current settings you may write a command like sis CTL minus eight on terminal to reload settings from sis CTL configuration file you can write sis CTL minus p to set a proc value dynamically, you can write the command with IP version four and the forward x parameter set to one and so on.

You can explore hardware devices with a snapshot of all connected devices which is being maintained by hardware abstraction layer, or ETL. In short, you can write command ATL, a slash dash device, which lists all the devices in text mode. Then you can write a command called a TL minus device minus manager, which displays all devices on the graphical window. Then there is a two other utilities, LS PCI and LSU elfi. This list devices connected to PCI and USB vs. It is similar to ls command Alicia which shows the directory the files and folders contained in a particular directory.

Similarly, the LS PCI and LS us we list all the devices connected on PC a and USB versus, respectively. The proc and sis file systems also So can inverse and devices specific information you can also go through them directly using the UI options. In there comes our monitoring the process and resources that are running on your system in the background and the foreground. informations available and a prop can be hard to understand directly, specifically for non developers or those who are not familiar to complete Linus kernel or First time users. You can go consider other things like the interfaces that are available to format the data and make it more accessible. You can go through memory process and kernel states, the memory could be accessible by free v Amistad.

So upon minus SP map, these are the commands or utilities that you can use to access the memory information, thought process information, you can write the command PS talk ps3 genome System Monitor which is a GI utility. And you can do check Colonel estate, you can write a command, you name up time, t load, and so on. These are the commands. If you just need to type this command, it will show you our various options. You can also check with manual command a man, VM stat. To get a complete list of the manuals.

This is a simple format. Nobody knows all the commands. Actually, you don't need to remember these commands. If you're finding it troublesome, you don't need to remember actually, you can go through the difference. You can download these videos, you can directly reference your work and go through the manual it will show you all the options available there. The arguments are not required to be memorized.

You just need to remember few commands of your use. Write a command right Ma'am, before writing the command man provide a space and your command name, it will show you the all the arguments and usage of the command which is simply a help option. That way you could learn the commands better. And you need to only remember those commands and argument which you need. There are thousands of commands or options available on a system, how much you can remember. So this was a simple kernel, configuration file and whatever we learned about kernel Linux kernel.

We will be exploring more in the coming videos so keep learning and keep moving ahead.