Linux Administration Fundamentals using RHEL 8 / CentOS 8 | Mostafa Mahmoud | Skillshare

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Linux Administration Fundamentals using RHEL 8 / CentOS 8

teacher avatar Mostafa Mahmoud, Data Scientist/ML Engineer/Linux Expert

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Get unlimited access to every class
Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Lessons in This Class

55 Lessons (6h 30m)
    • 1. Linux Administration Fundamentals Welcome to the Course Skillshare

      1:19
    • 2. Get Ready Section Overview

      0:33
    • 3. 01 Linux System Administration Introduction

      3:50
    • 4. 02 CentOS vs RHEL

      3:13
    • 5. 03 Installing Oracle VM VirtualBox

      3:29
    • 6. 04 Creating Virtual Machine

      3:18
    • 7. 05 Installing CentOS 8

      22:08
    • 8. Section One Overview

      2:51
    • 9. 01 CentOS 8 GUI Skills

      16:50
    • 10. 02 Starting a Terminal Window

      5:38
    • 11. 03 Centos 8 Virtual Consoles

      3:09
    • 12. 04 The Shell Basics

      15:07
    • 13. 05 The QuickStart Commands

      15:40
    • 14. 06 The Shell Special Keys

      4:20
    • 15. 00 Section Two Overview

      0:57
    • 16. 01 The Linux File System Hierarchy

      6:36
    • 17. 02 Managing Files Using Command Line Tools

      17:10
    • 18. 03 Matching File Names Using Path Name Expansion

      11:44
    • 19. 00 Section Three Overview

      1:10
    • 20. 01 Reading Documentation using man Command

      8:34
    • 21. 02 Reading Documentation using info Command

      1:09
    • 22. 03 Reading Documentation using pinfo Command

      4:18
    • 23. 04 Reading Documentation in /usr/share/doc Directory

      2:53
    • 24. 05 whatis command

      0:44
    • 25. 06 --help option

      0:44
    • 26. 07 Linux Graphical Help

      1:58
    • 27. 00 Section Four Overview

      0:59
    • 28. 01 The touch command

      2:43
    • 29. 02 Redirecting Output to a File or Program

      13:26
    • 30. 03 Editing Text Files from the Shell Prompt

      7:30
    • 31. 04 Editing Text Files with a Graphical Editor

      6:45
    • 32. 00 Section Five Overview

      1:56
    • 33. 01 Linux Users and Groups

      7:08
    • 34. 02 Gaining Superuser Access

      13:48
    • 35. 03 Managing Local User Accounts

      16:34
    • 36. 04 Managing Local Group Accounts

      6:44
    • 37. 05 Managing User Passwords

      18:13
    • 38. 00 Section Six Overview

      2:12
    • 39. 01 Linux File System Permissions

      10:20
    • 40. 02 Managing File System Permissions from the CLI

      16:30
    • 41. 03 Managing Default Permissions and File Access

      14:13
    • 42. 00 Section Seven Overview

      0:58
    • 43. 01 Processes

      1:57
    • 44. 02 The Life-Cycle of a Process

      2:46
    • 45. 03 Process States

      6:38
    • 46. 04 Listing Processes

      11:07
    • 47. 05 Controlling Jobs

      4:54
    • 48. 06 Killing Processes

      13:50
    • 49. 07 Monitoring Process Activity

      7:36
    • 50. 08 Real time Process Monitoring

      5:26
    • 51. 09 The System Monitor Tool

      3:50
    • 52. 00 Section Eight Overview

      1:31
    • 53. 01 Systemd

      5:43
    • 54. 02 Identifying Automatically Started System Processes

      11:49
    • 55. 03 Controlling Services and Daemons

      13:39
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About This Class

Linux Administration Fundamentals using RHEL 8 / CentOS 8

Hi, I'm Mustafa Mahmoud. A Senior Linux Administrator and Online Instructor. I have been working as Linux System Administrator for more than ten years, currently devoted to teaching. I like to share my knowledge with others and help them advance in their careers.

I prepared this course for newbie Linux users. By the end of the course, you will have acquired a solid understanding of the Linux Administration Fundamentals/Essential Skills using RHEL 8/CentOS 8 Linux!

Students testimonials - See what others say!

  • Siddharth Kumar: I really loved the course content and the way all details have been explained by the trainer, it will certainly help me or anyone else to improve their Linux administration skills.
  • Eric Voigt: Excellent overview of the basic skills, well organized and taught.
  • Suman Mandal: This course was useful to me. I have learned many things that were not clear to me. Thank you.

What you should know before starting

  • Basic knowledge of using a PC.

Requirements - A PC with the minimum requirement of installing RHEL 8 / CentOS 8:

  • x86_64 or ARM System
  • 2GB RAM (2GB minimum, 4GB recommended)
  • 20 GB unallocated disk space (10GB minimum, 20GB recommended)
  • Either a CD/DVD drive or a USB port for the installer media
  • Internet access is helpful

In this course you’ll learn: 

  • Linux System Administration Introduction
  • Installing VirtualBox
  • Installing CentOS 8
  • Linux System Administrator Essential Skills
  • Managing files from the command line
  • Getting Help in Linux
  • Creating, Viewing, and Editing Text Files
  • Managing Local Linux Users & Groups
  • Controlling Access to Files with Linux File System Permissions
  • Monitoring and Managing Linux Processes
  • Controlling Services and Daemons

 Contents

  • Get Ready!
    • Linux System Administration Introduction
    • CentOS vs. RHEL
    • Installing VirtualBox
    • Creating CentOS 8 Virtual Machine
    • Installing CentOS 8
  • Quickstart!
    • CentOS 8 GUI skills
    • Starting a terminal window
    • Centos 8 virtual consoles
    • The Shell basics
    • The Quickstart commands
    • The Shell special key
  • Managing Files from the Command-Line
    • The Linux file system hierarchy
    • Managing files using command-line tools
    • Matching file names using Path Name Expansion
  • Getting Help in Linux
    • Reading documentation using man command
    • Reading documentation using info command
    • Reading documentation using pinfo command
    • Reading documentation in usr/share/doc directory
    • whatis command
    • --help option
    • Graphical help in Linux
  • Creating, Viewing, and Editing Text Files
    • Redirecting output to a file or program
    • Editing text files from the shell prompt
    • Editing text files with a graphical editor
  • Managing Local Linux Users & Groups
    • Linux users and groups
    • Gaining superuser access
    • Managing Local User accounts
    • Managing local group accounts
    • Managing user passwords
  • Controlling Access to Files with Linux File System Permissions
    • Linux file system permissions
    • Managing file system permissions from the CLI
    • Managing default permissions
  • Monitoring and Managing Linux Processes
    • What is a process?
    • The life-cycle of a process
    • Process states
    • Listing processes
    • Controlling jobs
    • Killing processes
    • Monitoring process activity
    • Real-time process monitoring
    • The system monitor tool
  • Controlling Services and Daemons
    • What is systemd?
    • Identifying automatically started system processes
    • Controlling services and daemons

 I hope you benefit from the course!

Join me:

Meet Your Teacher

Teacher Profile Image

Mostafa Mahmoud

Data Scientist/ML Engineer/Linux Expert

Teacher

Hello, I'm Mostafa. A data scientist, ml engineer, and Linux expert. I worked for ten years as a Linux systems administrator at Express, then I had the opportunity to turn to data science. Because of my passion for this field and my keen attention to detail, I got my Udacity certifications to work as a data scientist and machine learning engineer. The most recent projects I worked on were Finding Donors for CharityML, a full exploratory and explanatory analytics work project for Ford Go Bike company trips data, and creating a logistic regression to predict absenteeism. I'm working on improving my skills and looking for job opportunities that will help me in this direction.

Skills: Python, SQL, Linux
Applications: Jupyter Notebook, Weka, Excel, Pycharm,... See full profile

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Transcripts

1. Linux Administration Fundamentals Welcome to the Course Skillshare: Hey there. Welcome to the Linux Administration Fundamentals course, where you will learn in the Linux Administration Fundamentals and essentially skills using the santos it Linux distribution. I am Mostafa Mahmoud. As in your Linux administrator and online instructor. I have been working as Linux system administrator for more than ten years, currently devoted to teaching. I like to share my knowledge with others and help them advance in their career leaves. Through this course, I will low hanging fruit for you. You will get a solid understanding of the fundamentals of Linux administration from where you can go through more advanced topics without suffering. This course is presented, we supported on the latest releases of Linux distributions like Red Hat, Enterprise Linux, Santos, Debian, and ubuntu. I prepared this course for new BY Linux users and no previous knowledge is needed. I only ask you to come open minded and ready to learn. Feel free to take a look at the course description, and I look forward to seeing you inside. 2. Get Ready Section Overview: In this section you will learn the Linux system administration job description. The Linux administrators, major deities. The main differences between centers and Red Hat Enterprise Linux. Virtual Box downloading and installing, creating a new virtual machine. And the steps of downloading and installing the sentence eight Linux. 3. 01 Linux System Administration Introduction: Linux system administration introduction. Linux is an operating system or a kernel created by leanest revolts with other contributors. It was first released on September 17th, 1991. The main advantage of Linux is that it is distributed under an open source license, which means we'll grammars can use the Linux kernel to design their own custom operating system. Linux is the perfect operating system for production servers and critical systems. Most Linux good is written in the c programming language. Linux has over 300 popular distributions that are being used all around the globe by users to provide their modern day computing needs and offering a variety of functions to them. The most important choices among Linux distributions or redhead centers, Fedora, Ubuntu, and DBN. I want to end DBN are used by a vast majority of home or desktop users. Red Hat Enterprise Linux and centers, short for community interprets operating system are two popular choices for servers operating system. Most of the observers, mobile phones, personal computers, supercomputers, and cloud servers are powered by Linux. The job of a Linux systems administrator is to manage the operations of a computer system like maintain, enhance, create user account, or an abort, taking backups using Linux tools and common line interface tools. Most computing devices are powered by Linux because of its high stability, high security, and open source environment. System Administration has become a solid criterion for any organization and the institute that requires a solid IT foundation. Hence, the need for efficient Linux administrator is the requirement of the time. The drug profile mighty change from each organization as there may be added responsibilities and duties to their own. The major duties of a Linux system administrator are maintain all internet requesters, inclusive to DNS, radius, Apache, MySQL, PHP. Taking regular backups of data, creating new stored procedures and listing backup, analyzing all error logs and fixing, along with providing excellent customer support for web hosting, ISP, and lend customers on troubleshooting, increased support troubles, communicating with the stuff, vendors and customers in uncultivated, professional manner at all times has to be one of his characteristics. Enhance, maintain, and creating the tools for the Linux environment and its users. Detecting and solving service problems ranging from disaster recovery to login problems. Installing the necessary systems and security tools. Working with the data network engineer and other personnel or departments to analyze hardware requirements and make acquiring recommendations. Troubleshoot when the problem occurs in the server. I hope this has been informative for you and I'd like to thank you for viewing. 4. 02 CentOS vs RHEL: Red Hat Enterprise Linux versus Center's. Red Hat Enterprise Linux is redhead official distribution. All of the redhead support services, service level agreements and certifications are based on Red Hat Enterprise Linux. It is intended to be an enterprise level, stable and secure operating system. Red Hat Enterprise Linux middle versions have a support cycle length of seven years with an option to extend up to ten years. Thus being a more stable and secure operating system. Although the source code of Red Hat Enterprise Linux is freely available, redhead restrict this, the redistribution of they're officially supported versions of Red Hat Enterprise Linux. To deploy Red Hat Enterprise Linux when a server or rock station, you have to purchase a subscription from redhead and renew it every year, except for a 30-day evolution version. This subscription entitles you to a few additional items such as support and batches. Centers. Centers is a community developed and supported alternative to Red Hat Enterprise Linux. It is similar to Red Hat Enterprise Linux but likes the enterprise-level support. Centers is a free replacement for it head Enterprise Linux with few minor configuration differences. It comes with an extended support lifecycle ranging from six to seven years, and it can be downloaded directly from the official website. Santos does tend to run a little behind Red Hat Enterprise Linux with releases. Minor releases can take hours or days to be deployed. And for middle releases, it can be several months. It might seem like an insignificant disadvantage. Having in mind that you get Centers for free. But for companies that think in terms of multiple year lifespans for the observers and software, the difference can be trivial. And important difference between redhead Enterprise Linux and centers is the access to repositories. And it was literally is the installation source used for installing software. If you are using free software such as centers, correct repositories are automatically set up and no further action is required. If you are using Red Hat Enterprise Linux with a subscription, you will get access to redhead repositories and that it had network. In this course. I will use centres it as it offers all features needed that treat head Enterprise Linux it offers without being for it. I hope this has been informative for you and I'd like to thank you for viewing. 5. 03 Installing Oracle VM VirtualBox: Now I will give you a short description about VirtualBox, and then I will show you how to download and install VirtualBox on your machine. Oracle VM Virtual Box is a free and open source hypervisor for X86 computers, currently being developed by Oracle Corporation. Virtual books may be installed on a number of host operating systems, including Linux, Mac OS, Windows, Solaris, and open Solaris. It's aborted the creation and management of the disk virtual machines running versions and the deviations of Windows, Linux, BSD, Solaris and others, and the limited visualization of MacOS guests on Apple hardware. For some guest operating systems, I guess the addition baggage of device drivers and system applications is available, which typically improves performance, especially of graphics. Go to the Visual Books website. Go to the download section. There are versions available for Windows, Mac and Linux. Download the Windows version at the top by clicking windows hosts. If your host operating system is Mac OS X, then you will click on Mac OS X hosts to download the.dmg file. And after finishing the unloading of in the file and follow the steps you'd see. Vet to Windows users. Start the installation. Resnik is to continue the setup wizard. Choose not to install USB support or by phone support. Do this by clicking the gray icon near each option and select the red X entire feature would be unavailable, leaving the VirtualBox networking rigid and host only enabled. Then click Next to continue. If this is your first time dealing with virtual machines, this would eliminate the need to uninstall custom drivers, which makes installing and uninstalling virtual Books easier. If you have working with virtual machines before, you can choose to keep this option selected. I'll check the default settings if you don't wish virtual books icons to appear on the desktop or that quick launch bar. However, keep the register file association books that chicken. This will ensure that files associated with virtual books open only with VirtualBox. Then Risk Next. Click Yes to proceed with installation. Click Mr. click finish to start the virtual books. I hope this has been informative for you and I'd like to thank you for viewing. 6. 04 Creating Virtual Machine: Creating a CentOS virtual machine. After starting virtual box, click the New button to start the Virtual Machine Wizard. Give you virtual machine and him. If you give it centers. The version will automatically default type to Linux and version two, red hat. Then click Next. Select the amount of memory your virtual machine will use. When we choose the operating system in the previous step, virtual box automatically recommends the proper amount of memory to use. The recommended value is 1GB. If the machine ram is 4GB, 2GB with the machine ram is EGB. Note that using RAM lower than 4GB is not recommended. For Headless servers. 1gb is enough, but for server with Graphical User Interface, it should be at least two GB. Here, you can choose 2GB or more than breast. Next, select Create a new virtual hard disk. Then click create. This opens a second wizard to create a new virtual hard disk. Choose VDI. Vdi is a virtual drive format used by the Oracle VM Virtual Box. Click Next. Select either fixed sizes storage or dynamically expanding storage, depending upon your needs, affects its size. Storage is going to be the size of the virtual hard disk on the host operating system. For example, a virtual disk, 20 GB will be 20 GB on the host operating systems hard disk, a dynamically expanding storage will be only the size of centres on your hard disk, but will grow in size as files are added to it until it reaches its limit. Select dynamically allocate memory. Click next. Selection of memory size 20 GB or more is recommended. Select the size of the virtual hard disk to be 20 GB. Click Create. Now you should see your centers virtual machine in the list. I hope this has been informative for you and I'd like to thank you for viewing. 7. 05 Installing CentOS 8: To download the centers it iso file. Go to the official website. Click on CentOS Linux DVD, ISO button. Click on the Miro link that is geographically closer to you. Your browser should start downloading the sense it iso installation image. It may take a while for the download to complete. After the sense it iso file is downloaded. Centers can be installed on physical as well as virtual hardware. First, installing centers physically. And this can be done using installation DVD or Habitable centers, USB. Creating a mutable centers USB stick from Microsoft Windows is very symbol and we are going to cover the process in the next few steps. You will need a GB or larger USB stick drive. Microsoft Windows seven or later. Rufus, which is a free and open source USB stick writing tool. Go to the Google search type Rufus, goto, the Rufus website. Click the download button. After the download is complete. Performed the following to configure your USB device in Rufus. Lunch, Rufus. Insert your USB stick. Rufus will update to set the device within the device field. If the device is incorrect, select the correct one from the device fields drop-down menu. To select the centers it iso file. Click select alongside the enabled create habitable desk using ISO image. This will open a file requester from which you can navigate to and select the ISO file. For best computability with newer hardware, keep the partition scheme and target system typeset as master boot record, MBR, unified Extensible Firmware Interface, UEFA. Leave all other parameters with their default values and click Start to initiate the writing process. If you are asking that there are files needed to be downloaded, agreed for the download. If this error a beers with you, follow these steps. Click the OK button. From the event log. Can be that the alluding address. Open Internet Explorer. In the address bar based the cabinet address. Then press enter. As you can see, to access this address, we need to turn on TLS 1.11.2. Click on the Change settings, find TLS. Click on the three TLS checkboxes. Then click OK. Now clues the Internet Explorer and try again. Click Start. Agreed for the download. You will be then alerted that Rufus has detected that the centers ISO is an iso hybrid image. This means the same image file can be used as the source for both additivity and a USB stick without requiring conversion. Key bright in ISO image mood selected, and click on OK to continue. Rufus would warn you that all data on your selected USB device is about to be destroyed. This is a good moment to double-check. You have selected the correct device before clicking OK. After checking, click okey. The ISO will now be written to your USB stick. And that progress bar in Rufus will give you some indication of how long this will take. With a reasonably modern machine. This should take around three minutes. Rufus will complete the writing process and silently drop back to its default window. Congratulations, you now have centered it on a USB stick, potable and ready to go. Once you set up your USB drive to be potable with centers, you can then reboot your system, Catch the boot menu, and boot from USP. If your computer doesn't automatically put from the USP, try holding F2 when your computer first starts. With most machines, this will allow you to select the USB advice from a system specific boot menu. It will lead you run a fully usable live CD version of centers it. Second, installing centers it using VirtualBox. Now, we will install sense it using virtual box. We will do this to keep your old breathing system as it is. So you can switch back to your old operating system anytime you want without any difficulties. And if you want to install sensors it directly to your machine, there is no problem. You can follow the same steps. Centers it installation requirements. A system with a minimum 20 GB of hard disk, two GB of RAM, and a good internet connection. Start VirtualBox. Select your centers virtual machine. Once you have done this, click the Settings spot-on. Click storage step. Click on Controller IDE, Ed's optical drive. Then press choose this proton to choose centers it iso file. Then press urban centers I x2 will be mounted under controller device. Click on the System tab on the left. Choose put order, and keep Optical on the top as the first periodicity. Press OK, to return to the main window. Your sentence machine is ready to boot now. To install since it select your virtual machine. Then click the start button. Centers Virtual Machine will start in a separate window. And you should see the grub boot menu. From this menu, you can choose from different options. Install centrist eight. Choose this for a normal installation. This, this media and install centers eat. Select this if you want to test the installation media before installing. Notice that this will take a significant amount of time. Troubleshooting. Select this option for some troubleshooting options. This option is useful if you cannot normally boot from your computer's hard drive anymore. Select Install centers, legs it from the graph menu and press enter. Choose your preferred language and click on continue. From here, you can set keyboard and installation source, software selection, type, kingdom, and installation destination. Now click on the installation destination. Select the virtual hard drive. For GNU Linux users. Click on the chosen local hard drive. Then select Automatic from storage configuration section. And click on Done. For more advanced users. You can select Custom from storage configuration section. The mixture that desk you want to use a selected and click Done to proceed. Choose LLVM partition scheme. Then click the plus sign to add new mount point. Llvm is short for Logical Volume Management. You can think of logical volumes as dynamic partitions, meaning that you can create, Resize, Delete LLVM partitions from the command line while your Linux system is running without needing to reboot the system to make the kernel aware of the newly created or resized partitions. Setting up the environment that is required in this course, I recommend using the following disclaimer out. Based on a Twinkie GB hard disk, you will need to configure a foreign sludge Boot partition size of 500 MB. Then click add mount point. And the device type choose Standard. And under File System choose x fs file system. Then click on update settings. The NFS file system is a highly scalable, high-performance file system that supports file system up to 16 byte, approximately 16 billion GB, files up to eight byte, approximately 8 billion GB. And directory structures containing tens of millions of entries. X fs supports metadata journalling, which facilitates quicker crash recovery. The NFS file system can also be the fragmented and resized while mounted and active. This file system is selected by default and is highly recommended. Click the plus sign to add new mount point forward slash for root partition with a size of ten GB. Think click, Add mount point button, and advice type choose LLVM. And under File System choose x fs formatted Logical Volume. Click the plus sign to add new mount points WEB with a size of 1GB logical volume that is used as swept species. Then click add marked point button. And the device type choose LLVM. And under File System choose swept. Click the plus sign to add new mount point slash home for the user home partition. Here, I will leave the desire to travesty blank to take all their meaning size from the 20 GB. Then click add mount point button. Under Device Type, Choose LLVM. And under File System choose x, fs. Now click on the Done button. You will see a summary of the changes we have made. Chick the summary, then click the accepted Changes button to write your configuration. Now click on network and host name. It is off by default. Switch it on. Type in the hostname and click on apply. Then click on done. If you want to install, since it's a river with graphical user interface, then you don't have to do anything else. But if you want to install since it headless server thing, click on software selection. Then select server and click on Done. But here, we will leave it with the graphical user interface. If you want to set up your time Xun, click on time and did. Select your region and city. And click on done. Now to configure Kingdom. Kingdom is used to set up a process that is started with your server to allow you to create a memory cool damping case, the kernel crashes. If your server does have enough RAM available, that will result in keydown being active automatically. If your server is low on memory, you won't have it running by default. As Linux kernel crashes don't occur very frequently and S sitting up kingdom is not apart of the ROHC or our MHC-II objectives. You can just disable kingdom and click that button. Once you are done, click on begin installation. The installation should start. Now you have to enter the root password. Click on the root password button. Type u root password. Confirm it. Click on done. Now to create a new login user. Click on User creation. Type in the new user personal information. You can check the mic, this user administrator checkbox to make this user administrator. But here, I need a normal user because logging in with administrator privileges has a lot of risks. So we will need a regular user while using the system in normal tasks. Type the new user password. Confirm it. Link click on done. Once the installation is complete, click on reboot. Virtualbox Virtual Machine may put from the sentence it installation DVD. Again. To avoid that, click on devices. Choose optical drives. The choose remove disc from virtual drive. Click on force amount. Now, click on machine. Choose reset. To reset the virtual machine. Click on reset to confirm the action. The virtual machine should boot from the virtual hard drives. One sentence, it boots. We will complete the initial setup. Click on license not accepted. Read the license, then check the I accept the license agreement. Checkbox. Then click done. Click Finish configuration. You can login using the username and password that you have set during the installation. Click on the username, typed the password, then press enter, or click on the Sign In button. Now, the genome initial setup wizard will open. Choose your preferred language than breast. Next. Select your keyboard layout than breast. Next. Choose to let applications access your location or not. The embrace. Next. You can connect with your online accounts or presses, skip. Presses, start to start using centers. It they're getting starting guide will open. You can preview it if you wish or close this window. Steps for adjusting the resolution to view a full resolution centers virtual machine on your computer. Click the System menu in the top right corner to manage your system settings. Click on the System Settings icon. Click on the icon, finds plays, and click on it. Choose the suitable resolution for your screen. Then click the Apply button. Click the Q Changes button. Now you are viewing a full resolution centers it virtual machine on your computer. I hope this has been informative for you and I'd like to thank you for viewing. 8. Section One Overview: In this section you will learn Red Hat Enterprise Linux it and centers it Linux system administrator, essentially skills which will include santos Eight graphical user interface connecting to the system using graphical mood. Visual overview of gloom three, the top bar, the system menu in the top bar. Activities button, overview. Starting applications, workspaces, switching between workspaces, launching and application in several talks piece, lodging and application in your workspace. Quickly running A-command. Application, menu, clock and Calendar button. New boxes features. The system menu, lacking the screen switching users suspending the computer, barring off the computer, switching between windows. The difference between terminal and chin. Launching the terminal window, the terminal window command Brom bit. Checking your hostname, switching to root user, disconnecting from the system in graphical mood, center skied virtual consoles, the text would login screen, logging in using a Virtual Console. The TTY comment that look outcome and the shell B6, the best shell. The shell commands basic parts, the shale areas. This built in comments. The external commands, the path environment variable, the which command? The equal command, the command. Changing directories in the bath variable. The export command, the environment configuration files using of him RTD and issue files. Shell commands, typing rules, Quickstart commands. They did Kim and the PWD command. The cd command, relative and absolute path is the best route command. The file command, the head and tail commands, the WordCount command, the GET command, the exit command, the ls command, the history command, the exclamation point character. The shell, special keys. 9. 01 CentOS 8 GUI Skills: Centers it graphical user interface. To work on a Linux system directly, you will need to provide a username and a password. Linux systems have two basic modes for a system to run in. Either quick and sober in thickest console mood, which looks like this with mouse multitasking and the multiuser features. Or in graphical mood, which looks better, but it's more system resources. Here, the default graphical mode of the centers it desktop environment is 3.28. The graphical mode is the default nowadays on mostly desktop computers. You know, you will connect to the system using graphical method when you are asking for your username and password. To log in, click on your username and enter your password to the system and click OK or breast Enter. It can take a little while before the graphical environment is started. Depending on the CPU speed of your computer, the software you use, and your personal settings. It is considered a bad idea to connect graphically using the root user name, which is the system administrator's account. Since they use of graphics includes running a lot of extra programs in roots case, with a lot of extra permissions. So to keep all risks as low as possible, use a regular user account to connect graphically. But there are enough risks to keep this in mind as a general advice, for all use of the root account. Only log in as root when extra privileges are required. Since it column three, overview is a free and open source desktop environment for Unix-like operating systems. The gloom three features, a completely re-imagined user interface design to stay out of your way, minimize distractions, and help you get things done. When you first log in, you will see an empty desktop and the top bar. The top bar provides access to your Windows and applications, your calendar and appointments. And system Roberta's like sound it working and power. In the system menu in the top bar. Ok, change the volume or screen brightness. Edit your Wi-Fi connection details. Check your battery status. Look out all switched users, and turn off your computer. To access your Windows and applications, click the activities button or just move your mouse pointer to the top left corner. You can also press the super key on your keyboard. You can see your Windows and applications in the overview. Also, you can just start typing to search your applications, files, folders, and the web. On the left of the overview, you will find the dish that shows you your favorite and running applications. Click any icon in the desk to open that application. If the application is already running, it will be highlighted. Clicking its icon will bring up the most recently used window. You can also drag the icon to the overview or onto any workspace on the right. Right-clicking the icons plays a menu that allows you to pick innuendo in running application or to open a new window. You can also click the icon while holding down control to open a new window. When you enter the overview, you will initially be in the Windows overview. This shows you live thumbnails of all the windows on the current workspace. Click the grid button at the bottom of the dish to display the applications overview. This shows you all the applications installed on your computer. Click any application to run it, or drag and application to the overview or onto 4G speeds thumb be_nil. You can also drag an application onto the desk to make it a favorite. Your favorite applications stay in the dish even when they aren't running, so you can access them quickly. There are several ways of opening and application. Once you are in the activities overview, start typing the name of an application. And you will notice that sensing begins instantly. If this doesn't happen, click the search bar at the top of the screen and start typing. If you don't know the exact name of N application, tried to type a related term. If you connect the grid button at the bottom of the dish, you will see the frequently used applications with the frequent view is enabled. If you want to run a new application, press the All button at the bottom to view all the applications. Then press on the application to start it. Workspaces. Workspaces are separate desktop screens which have different application windows. These can be used to organize the working environment by grouping open application windows by task. For example, Windows being used to perform a particular system maintenance activity, such as setting up a new remote server, can be grouped in one workspace. Y, email, and other communication applications can be grouped in any other workspace. There are three methods for switching between workspaces. One method is to click the indicator in the right corner of the window list and select the desired workspace. Another way, perhaps the fastest, is to type Control up arrow or Control down arrow to switch between all species sequentially. A third way is to switch to the activities over view and click the desert workspace. You can launch an application in a separate workspace by dragging its icon from the dish and dropping it onto one of the works pieces on the right hand side of the screen. The obligation will open in the choosing workspace. Also, you can launch an application in a new workspace by dragging its icon to the empty workspace at the bottom of the workspace switcher, or to the small gap between two workspaces. Another first way of launching and application is to press Alt F2, that enters its common name. And then press the Enter key. Here, the name of the app is the command to launch it. You can use the arrow keys to quickly access previously run commands. Application menu. The application menu located beside the activities button. It choose the name of the active application alongside with its icon and provides quick access to Windows and the details of the application, as well as acquit, item, calendar and appointments. You can click that look on the top bar to see the current deed. A month by month calendar, a list of your upcoming appointments and the new notifications. You can also open the calendar by bracing Zuber and M keys together. You can access the date and time settings and evolution can enter directly from the menu. New boxes, features. Boxes. The gloom application for using remote and virtual machines has a number of new features and enhancements. For gloom, 3.281 major new feature is automatic downloading of operating systems straight from the new books assistant. To create a virtual machine. All you have to do is to pick the operating system you want to use, and boxes will do the rest. The new version of boxes also makes it easy to transfer files between your computer and virtual machines. To transfer files, you can either drag and drop them on the boxes window or select the same file's option and select files to be transferred using a file chooser. In both cases, boxes provides feedback about the progress of file transfers. So you know how long they are going to take, as well as when they have finished. The system menu. Click the System menu in the top right corner to manage your system settings and your computer. When you leave your computer, you can look your screen to prevent other people from using it. You can also quickly switch users without logging out completely to give somebody else access to the computer. Or you can suspend or power of the computer from the menu. If you have a screen that supports vertical or horizontal rotation, you can quickly read the screen from the System menu of yours. Clean doesn't support rotation. You will not see the button. When you look, you will screen or it looks automatically. The lock screen is displayed. In addition to protecting your desktop while you are away from your computer. The lock screen displays the date and time. It also shows information about your battery, ad network status. Switching between windows. You can see all the running applications that have a graphical user interface in the window switcher. This mix, switching between tasks, a single step process, and provides a full picture of which applications are running. From our workspace. Press Subaru plus step to bring up the window switcher. Released Zuber to select the next highlighted window in the switcher. Otherwise, still holding down the super key breast step to cycle through the list of open windows. Or Shift plus Tip two cycle backwards. You can also move between the application icons in the window switcher with the right or left keys, or select one by clicking it with the mouse. Previews of applications with a single window can be displayed with the down arrow key. From the activities Overview. Click on window to switch to it and leave the overview. If you have multiple or species or bin, you can click on each workspace to view the urban windows on each workspace. I hope this has been informative for you and I'd like to thank you for viewing. 10. 02 Starting a Terminal Window: Starting the terminal window. Before starting, I'd like you to know the difference between the terminal and the shell. The terminator refers to a rubber program which runs a shell. While the shell is the program which actually processes commands and the return is output. To lunch, the terminal window. Click on activities. And in the search bar type terminal. Then click on the terminal icon. All click on activities. Choose terminal if a beer or click on activities. Then click on Show Applications, thing click on All. And from utilities, click on terminal. The terminal window is your control panel for the system. Almost everything that follows is done using the simple but powerful tool. A terminal window should always show a comment Brom bit. When you open it. Once you launch the terminal, you would find something as mu it, my dot centers, dot server, tilda, dollar sign written on it. The first part of this line, Mu, is the name of the user. The second Bart, my two centers to observer if the computer name or the host name, which we added during the installation. The hostname help is identifying a computer over the network. In a server environment, the host name becomes important. You can use this command to check your hostname. Echo, dollar sign. Hostname. The Delta sign shows that the user is working in the home directory. You can check using the PWD comment. If you change the directory, the sign will vanish. For example, if we moved from my home directory to slash bin using the cd command, the tilda sign will be changed with the current directory name. It will appear again when moving back to the home directory, either by using the comment cd slash home slash user name, or by typing the command cd only, or by typing the command cd tilde. And pressing enter. The dollar sign suggested that you are working as irregular or standard user. While working as a root user by typing the SU Bash command, pressing Enter, followed by the root password. The hash will be displayed and the user name will be changed to route. To disconnect from the system in graphical mood, you need to close all terminal windows and other applications. After that, click the System menu in the top right corner, then hit the power button. And you choose either to reboot or to shut down the system as needed. Or click on the username. Then click on Log out. Closing everything is not really necessary and the system can do this for you. But session management might put all currently open applications based on your screen. When you connect again. When you see the login screen, again, asking to choose a username, then look outwards. Successful. I hope this has been informative for you and I'd like to thank you for viewing. 11. 03 Centos 8 Virtual Consoles: Santos virtual consoles. A Virtual Console is attempts to console. You can use a terminal window to issue shell commands. However, you can. So shell commands, even when x is not running or available using the Linux Virtual Console. Linux provides six virtual consoles for interactive use. The first second, virtual consoles are associated with the graphical user interface. You can use a special keystrokes to switch between virtual consoles with a graphical environment running X's are thickest login Brom bit on Virtual Console by holding Control Alt and pressing a function key from F3 to F6. You can view only a single console at a time, but you can switch rabidly between consoles by using the appropriate keystroke. Thickest mood login screen typically shows some information about the machine you are working on, the name of the machine and a Brom bed waiting for you to login. To login using a Virtual Console, type your username and press enter. The system will prompt you for the password associated with your account. Type your password, and press Enter. To prevent anyone nearby from learning your buzzword. Linux doesn't display your password as you enter it. If you suspect you have typed it incorrectly, you can either hit the backspace key several times, sufficient to delete the characters you have entered. When the system has accepted you as a valid user, you'll be given a shell indicated with the same robot that you would get in graphical mood. Also in thickest mood, login as root only To-Do setup and configuration that requires administrator privileges, such as adding users and installing software packages. And we're forming network and other system configuration. Once you are finished, immediately leave the special account and resume your work as a regular user. You can check that in MLA you are connected to using that IT UI comment. Logging out is done by entering the drag out command, followed by Enter. You are successfully disconnected from the system. We knew C, the log in screen. Again. You can press Control Alt F1 or F2 to return back to the graphical desktop. I hope this has been informative for you and I'd like to thank you for viewing. 12. 04 The Shell Basics: The shell basics. The shell is the default working environment for Linux administrator. It is the command interpreter in any Linux operating system. The shell is a program that executes other programs. It provides a computer user and interface to the Linux operating system so that the user can run different commands or tools with some input data. When the cell has finished executing a program, it sends an output to the user on the screen, which is the standard output device. For this reason, it is referred to as the comment interpreter. The shell is much more than just a comment interpreter. It is also a programming language of its own with complete programming language constructs such as conditional execution, loops, variables, functions, and many more. That's why that new Linux shell is more powerful compared to the Windows shell. Differentials for Linux are available, but bash is the common shell. So when we are talking about the shell in this course, we are talking about the bash shell. Bash standards for bourne, again shell, and it is a default shell on many Linux distributions today. It is also a bourne shell compatible shell and offers practical improvements over the Bourne shell for programming and interactive use, which includes command line editing, job control, or limited size comment history, chill functions and aliases. A limited size indexed arrays, integer, arithmetic in any base from two to 64. Comments entered at the shelf rhombic have three basic parts. Comment to run. Options to adjust the behavior of the command. Arguments which are typically targets of the comment. The comment is the name of the program to run. It may be followed by one or more options, which adjusts the behavior of the command or what it will do. Options normally start with one or two dashes to distinguish them from arguments. Comments may also be followed by one or more arguments, which often indicate a target that the command should operate on. The shell makes a difference between three kinds of commands. Aliases, internal commands. In the external commands. A shell ls is a shortcut to reference a comment. It can be used to avoid typing long comments. For common patterns, it can reduce keystrokes and improve efficiency. A simple example is sitting default options on comments to avoid having to type them each time a comment is run. Some aliases are provided by default. Type alias on the common line. To get an overview. To define an alias. Use LES. New command equals sign. All the comment. As in the default, alias, L, L equal ls, dash l, dish, dish, color equal. To. Note that aliases are executed before anything else. Second best built-in commands, also known as internal comments, are part of the shell itself. Each built-in command is executed directly in the shell itself instead of N External programs which are the base, would load and run. You can show the list of built-in commands using the help command. An example of internal or built in command is alias comment. While the top comment is an example of the external command. To find out whether a given command is n internal, built-in or external. You can use the type comment. For example, Type II, cd. Type. This e to the dollar sign Beth is n environmental variable in Linux and other Unix-like operating systems that tells the cell Ricci directories the executable programs are located when a user enters a comment. To find out which exact comment the shell will be using. You can use the which command, for instance, type which ls to find out where the shell will get the LS comment from. You can use the echo command to show the contents of the dollar sign variable by typing echo dollar sign Beth, which leads the current value of the bet variable and rents that on the standard output. Also, you can get an overview of the parent variables defined in your shell environment by typing the comment. When you want the system to execute a command, you really have to give the full path to that comment. For example, we know that the LS comment is in the slash bin directory. You can check with which ls. Yet we don't have to enter the comment slash bin slash ls for the computer to list the content of the current directory. The Beth environment variables takes care of this. This variable list is those directories in the system where executable files can be found. And thus gives the user a lot of typing and memorizing locations of comments. So the Beth naturally contains a lot of directories containing bend somewhere in their names to check, type echo, dollar sign. Beth. As soon as match is found, the search is stopped. Even if not every directory in the Beth has been circulated. If you use programs in other trajectories more frequently, you can change your Beth to look in your directories. For example, to add your slash home slash downloads directory. We can use the export comment, export Beth equal. We will enter the old Beth data, followed by colon slash home slash downloads. Then press Enter. Note that here changes are not permanent. When using the export command in a shell. That changes are temporary and only valid for this session. Opening new sessions even while the current one is still running, will not result in a new Beth in the new session. To make it permanent, you need to add the export Beth command to your home slash movie slash dot profile file or home slash mooc Slashdot best RC file. For example, to add home slash downloads to the Beth variable in the home slash mooc Slashdot page RC file. Here, I will use the nano editor to open the dot dash RCF file for editing. Nano dot this RC. Press enter. And at the end of this file, it export. Beth equal dollar sign Beth colon slash home slash downloads. Here I bought dollar sign Beth, to keep the old Beth as it is, or it will be removed and you will only see the slash home slash downloads Beth. Press Control X. Then press White to confirm saving and press Enter to confirm using the same name and exit. Note that This will not automatically update your Beth for the remainder of the decision. To do this, you should run source the Beth to do this RC file or RC file if you are in the same directory. And press Enter. Let's check echo. Dollar sign, pith. Note that for the root user, you will do the same steps but on the sludge ETC. Slash profile file or the sludge ETC. Slash bash. Our C5 environment configuration files. When a user logs in and environment is created for that user automatically. This happens based on four different files where some script could, can be specified and where variables can be defined for use by one specific user. Sludge, ETC, slash profile file. This is the generic file that is processed by all users upon login slash slash base or C file. This file is processed when sub-shells are started. User home directory slash. The best underscore profile phi in the user home directory. In this file uses a specific ligand shell variables can be defined. And the best RC file in the user's home directory. In this user specific file, sub-shell variables can be defined. In this finds, a difference is made between a lagging shell and a sub-shell. I login shell is the first shell that is opened for a user after the user has logged in. From the ligand shell, a user may run scripts which will start a sub-shell of that login shell using sludge, ETC, slash, NOT defiled, end stage, ETC. Slash issue phi less offers an option to include messages in the sludge, ETC. Slash M, O T, D, and the slash ETC. Slash issue files. Messages in the sludge, ETC. Slash RTD display after the user has successfully logged into a shell. Notice that users in a graphical environment don't see its contents after a graphical login using sludge, ETC. Slash M O T D can be a convenient way for system administrators to inform users. Another way to send information to users is by using sludge, ETC. Slash issue file. The contents of this file displayed before they user logs in. This provides an excellent means of satisfying specific login instructions to users who aren't logged in yet using thickest user interface. For example, nano slash, ETC. Slash issue. At some data. Press Control X. Then press wide to confirm sieving. And press Enter to confirm using the same name and exit. Now press control alt F3. As you can see, the data I have entered is appearing up. I hope this has been informative for you and I'd like to thank you for viewing. 13. 05 The QuickStart Commands: The Quick Start commands. Each string typed into the shell can have up to three parts. The command options that begin with a dish or double dish, and arguments. Word tied into the shell is separated from each other with the species. Commands are the names of programs that are installed on the system. Each command has its options and arguments. The Enter key is pressed when a user is ready to execute a comment. Each comment is typed on a separate line, and the output from each comment displays before the shell displays abroad bit. If a user wants to type more than one comment on a single line, a semicolon can be used as a comment separator. A semicolon is a member of class of characters called meta characters that has a special meanings for Bash. After launching the terminal. Now, we will have a look at the Quick Start commands that did comment is used to display the current date and time. Type D it then press Enter. The did comment can also be used by the sober user to sit the system clock. An argument that begins with a plus sign specifies a format string for the deed comment. For example, we'll use the comment did plus person sign, uppercase R to show that time formatted hours, colon minutes. And we use the command D8 plus person sign, lowercase x to show the date formatted month slash day slash year. The PWD command print working directory comment used for displaying the current working directory. The CD comment, change directory comment used for changing directories. Type cd forward slash. To move to the root directory. It is important to not forget space between SCD and forward slash. Otherwise, you will get an error. The root of the file system in Linux is denoted by forward slash, similar to C colon backslash in Windows. Note that in Windows you use backward slash. While in Linux system, the forward slash is used. You can navigate through multiple directories at the same time by satisfying it's complete. But for example, if you want to move to the CPU directory under the slash dev directory, we don't need to break this operation into two parts. And instead, we can type CD slash dev slash CPU to reach the directory directly. For navigating up one directory level, we can use cd dot dot. We can check using the BWT comment. Here by using the cd double-dot comment, we have moved up one directory from slash dev slash CPU to slash dev directory. Then by again using the same comment. We have jumped from slash dev slash, which is the root directory. Relative and absolute battles. Above in computing is the address of a file or folder. For example, slash home slash movie slash downloads. This is the best for the Downloads directory. There are two kinds of paths. First, absolute path. Let's say you have to browse the images stored in the pictures directory of the home folder mu. The absolute file path of pictures directory is slash home slash movie slash pictures. To navigate to this directory, you can use the command cd slash home slash movie slash pictures. This is called absolute path, as you are specifying the full path to reach the file. Second, relative Beth. The relative Beth comes in handy when you have to browse and other subdirectory within a given directory. It saves you from the effort to type complete path is all the time. Suppose you are currently in your home directory slash home slash mooc. You want to navigate to the Downloads directory. You don't need to type the absolute path CD slash home slash movie slash downloads. Instead, you can simply type cd downloads. And you would navigate to the Downloads directory as you are already present within the slash home slash MOOC directory. This way you don't have to specify the complete path to reach a specific location within the same directory in the file system. The best would comment changes a user's password. The original password for the account must be satisfied before a change will be allowed. By default, password is configured to require a strong password consisting of lowercase letters, uppercase letters, numbers, and symbols. And is not based on a dictionary or a note that the super user can use the basswood comment to change other users passwords. For example, to change my password as user move westward and press enter. First, I will need to enter the old password. Then the new buzzword. And again retype the new buzzword. And as the root user to change the user move password, type the command best would move. Then x doesn't require file name extensions to classify files by type. The file Comment scans the beginning of a file's contents, ends plays what type it is. The files to be classified? Our bust as arguments to the comment. For example, file slash ETC, slash password. Another example, file slash home. The head and tail commands splay the beginning and end of a file respectively. By default, these comments display ten lines, but they both have a dish in option that allows a different number of lines to be specified. The file to display is best as an argument to these comments. For example, head slash, ETC, slash basswood. And to show the last three lines in the best route file, you can use the command till this n, three slash ETC. Slash password. Or you can type pill dash three slash ETC. Stage password. The WC comment counts, lines, words, and characters in a file. It can take a dash l, dash w, or dash c option to display only the lines, words or characters respectively. For example, WC, sludge, ETC. Slash password. And to show the number of lines only WC dash l. It is he slash password. And to show the number of characters in two files and the total of the characters in the two files. Wc. This C slash ETC, slash, group, space slash ETC. Slash hosts the cat command through the content of any text file on the screen, for example, kit slash, ETC. Slash hosts. The exit comment is used to leave this session. The ls command to list the satisfied directory content. An example is ls slash, ETC. Where did the directory slash ETC, is the argument to the LS comment. This indicates that you want to see the content of that directory instead of the default, which would be the content of the current directory obtained by just typing ls followed by inter. Some commands required arguments. Sometimes arguments are optional. You can find out whether a common takes options and arguments and which ones are valid by checking the align help for that comment, which we will discuss later. The history comment displays a list of previously executed commands, prefix it with a comment number. The exclamation point character is a meta character that is used to exhibit previous comments without having to retype them. Exclamation sign, followed by number. Expense to the common matching, the number specified. And exclamation followed by string expands to the most recent command that begins with the string specified. For example. Or you can redo a command that was done before by satisfying its number from the history after the exclamation, mark, for example, history. Then you choose a comment and satisfy its number. Now to redo it. Exclamation mark, followed by the number and brisk enter. The arrow keys can be used to navigate through previous command lines in the shells history. Up arrow it, it's the previous command in the history list. Down arrow it, it's the next command in the history list. Use this key when the up arrow has been pressed too many times. Left arrow, right arrow. You can use left arrow, right arrow to move the cursor left and right in the current common line being edited. I hope this has been informative for you and I'd like to thank you for viewing. 14. 06 The Shell Special Keys: The shell is special keys. Using best features, several special key combinations allow you to do things easier and faster with Agnew shell fish, which is the default on almost any Linux system, you are strongly suggested to make a habit out of using them so as to get the most out of your Linux experience from the very beginning. Now, let's try some examples. Press Control a to move the cursor to the beginning of the comment line. Press control C to end a running program and return the Braam bit. Press Control D to lug out of the current shell session. It is equal to typing exit. And if you are using the root user, it will switch to their regular user. Press control, ie, to move the cursor to the end of the comment line. Press Control H, two generic backspace character. Press control you to clear from the cursor to the beginning of the comment line. Press control key to clear from the cursor to the end of the comment line. Press Control L. To clear this terminal. Brisk control are to search in command history for a particular comment. This arrow left or arrow right, to move the cursor one place to the left or right on the command line, so that you can insert characters at other places than just at the beginning and at the end. Press arrow up or arrow down. To browse history. Go to the line that you want to repeat. It. It details if necessary, and press enter to save time. Press shift up or shift pitch down to browse the terminal buffer to see thickest that has scrolled off the screen. For example, kit slash, ETC. Slash password. And try shift up or shift beach down. Tab completion allows a user to quickly complete comments or file names once the have typed enough at the Brahmin to make it unique. For example, BC. And press Tab to complete the comment. With the characters typed are not unique. Pressing the tip key twice displays all commands that begin with the character's already typed. For example, PAS. And please step twice. The result will be, as you can see, then you can choose the best choice for you or they'll acquire the choice. I hope this has been informative for you and I'd like to thank you for viewing. 15. 00 Section Two Overview: In this section, you will learn managing files from the command line, which will include the Linux file system hierarchy. The most important directories on the Linux system came out line file management, creating, deleting, copying and moving files and directories. The touch command, more options for cd and Ls commands. Matching find names using Beth name expansion. The command meta characters and better in classes. Symbol better matches using question mark, tilda expansion, brace, expansion, command substitution, predicting arguments from expansion. 16. 01 The Linux File System Hierarchy: The Linux file system hierarchy. Assemble description of the Linux system is that when a Linux system, everything is a file. If something is not a file, it is a process. A Linux system makes no difference between a file and directory. Since a directory is just a file containing names of other files, programs, services, texts, images, and so forth are all files, input and output devices. And generally, all devices are considered to be files according to the system. In order to manage all those files in an orderly fashion, we will think of them in an order, the tree-like structure on the hard disk. All files on a Linux system are stored on file systems which are organized into a single inverted tree of directories known as a file system hierarchy. This tree is inverted because the root of the tree is said to be at the top of the hierarchy. And the branches of the directories and subdirectories stretch below the root. The directory forward slash is the root directory at the top of the file system hierarchy. The forward slash character is also used as a dielectric disability in file names, for example, if, ETC, IS a subdirectory of the root directory, we could call that directory forward slash, ETC. Likewise, if their forward sludge ETC, directory contains a file named hosts, we could refer to that file as forward slash, ETC. Forward slash hosts. Subdirectories of the root directory are used for standardized purposes to organize files by type and verbose. This makes it easier to find files. For example, in the root directory, the subdirectories slash boot is used for storing files needed to boot the system. The following terms are encountered in describing filesystem directory contents. Static is contended that remains unchanged until explicitly edited or reconfigured. Dynamic or variable. Is content typically modified or appended by active processes? Resistant. Is content particularly configuration settings that remain after a reboot. Runtime is process or system specific content or attributes. Clearly during reboot. The most important directories on the Linux system. User directory. For installed software. Shared libraries include files and static read-only program data. Slash user important subdirectories include. Bin directory for user commands. It's bin directory for system administration commands. And local directory for locally customized software. It is he directory for configuration files is specific to this system. Var directory for variable data specific to this system that should be recessed between boots, files that dynamically changed. For example, databases, cache directories, log files, printers pulled documents, and website content may be found under slash br, r1 directory for Runtime Data for processes started since the last boot. This includes versus ID files and log files, among other things. The contents of this directory are recreated on reboot. Home directory. For home directories where regular users store their personal data and configuration files. Root directory for one directory for the administrative superuser, root TMP directory is awarded writable speeds for temporary files, files which are more than ten days old or deleted from this directory automatically. Another temporary directory exists. This is slash var slash t MB, in which files that haven't been accessed, a changed or modified in more than 30 days or deleted automatically. Boot directory. For files needed in order to start the boot process. Dev directory contains a special device files which are used by the system to access hardware. Min directory, lib directory, lip 64 directory, and Espen directory. In older versions of centers and Red Hat Enterprise Linux, these weird distinctive directories containing different sets of files, incentives it, and Red Hat Enterprise Linux, it, these directories in the root directory or symbolic links to the matching directories in the slush user directory. I hope this has been informative for you and I'd like to thank you for viewing. 17. 02 Managing Files Using Command Line Tools: Managing files using command line tools. Command line file management. File management involves creating, deleting, copying, and moving files. Additionally, directories can be created, deleted, copied, and moved to help organize files logically. When working at the common line, file management requires awareness of the current working directory to choose either absolute or relative bed syntax as most efficient for the immediate task. Creating files. The touch command normally updates a file's timestamp to the current date and time without otherwise modifying it. This is useful for creating empty files, which can be used for practice, since touching a fine name that doesn't exist causes the file to be created. For example, here we are in the user move home directory. Now for listing files in directories in this directory, we will use the LS comment, followed by dash l option for a long listing format. For our example, we would work on the text file. To check the content of the text file, we will use the cat command. Now, enter the command touch thickest to update the text file timestamp. Now to check the update. As you can see, the textFile timestamp is updated to the current date and time. And to check the content. Here, as you can see, that text file timestamp is updated to the current date and time without otherwise modifying it. Also, you can use a text editor program like Vim or nano to create a new file or modify the existing one. For example, nano fruits. The new file will open. You can add some data. Then Save and Exit to check. And to show the data in the fruits file using the cat command. Although SBS is n acceptable character in Linux file names as Bs is the delimiter used by the common shell for comments in texts interpretation. New administrators are advised to avoid using species in file names. Since filenames that includes pieces frequently result in undesired command execution behavior. The ls command has multiple options for displaying attributes on files. The most common and useful options are this e, option for displaying all files, including the hidden files. The two special directories at the top of the listing referred to the current directory with dot and the barren directory with double-dot. These special directories exist in every directory on the system. The usefulness will become apparent when fight management commands our breakfast. File names beginning with a dot indicate files hidden from normal view using ls and other comments. This is not a security feature. He didn't files keep necessary user configuration files from cluttering home directories. Mini commands process hidden files only with a specific command line options with eventing one users configuration from being accidentally copied to other directories or users. To protect file contents from improper viewing requires the use of file permissions, which I will discuss later. The hidden directory dot satisfies the current directory on commands in which the current location is either the source or destination argument, avoiding the need to type out the directory's absolute pathname. When using the cd double-dot comment, it uses the double-dot hidden directory to move up one level to the barren directory without needing to know the exact parent name. For example, here we are in the user's home directory by using the CDW.com and we have moved up one level to the barren directory slash home. The dish uppercase r, recursive option to include the contents of all subdirectories. Here, as you can see, the contents of the Downloads directory and the contents of the mixtures directory. This l option for long listing form it. By adding the dash l option to ls command. It can list all the files, directories, and their mood, number of links, owner of the file, file size, Modified Date and Time, and filename. Also, you can use L L instead of ls dash l. As ls dash l is aliased to L. L. You can check using the alias comment. Creating directories. They make dire comment, creates one or more directories or subdirectories generating errors if the filename already existed or when attempting to create a directory in aberrant directory that doesn't exist. The DSB Barend option creates missing barren directories for the requested destination. Be cautious when using McGuire DSB. Since x dental spelling mistakes create unintended directories without genetic error messages. For example, to create 2019 directory, make their 2019 to check. And to create Jen directory and subdirectory for the 20-20 directory. Make their 20-20 slash Jane. The make Deerfield due to existing one of two reasons. First, 20-25 years misspelled, or 20-20 doesn't exist as allocation in which to create the gin subdirectory. As in this case. Here, if a DSP option we've used, we wouldn't have received an error message and we will have the two directories, 20-20 and Jen created. For example, make dire Thisbe 20-20 sledge Jan. To check here that SB parent option created the missing barren directory 20-20, and the subdirectory Jane. Copying files. The CB comment, cabbies one or more files to become a new independent files. Syntax allows copying an existing file to a new file in the current or another directory, or carrying multiple files into another directory in any destination, new file names must be unique. If the new file name isn't unique, that public comment would overwrite the existing file. For example. Here I will work on the text file to show that text file contents. Now to copy the text file to the 2019 directory. To check the lobbying has succeeded, and to check that the contents of the text file hasn't been modified. If we modified the original text file using the nano program. Then save and exit. Copy it again to the 2019 directory and check the data in the text file in the 2019 directory using the CAD comment. As you can see, the all the text file is released with the new one because they are using the same name. When combining multiple files with one comment. The last argument must be a directory. Debate files edit in the original names in the new directory. Conflicting filenames that exist at a destination may be overwritten to protect users from accidentally overwriting directories with contents, multiple file CB comments ignored directories is specified as a source. Copying and an empty directories with contents requires the dish lowercase or recursive option. For example, to copy the fruits file to that 20-20 slash Jane directory. Cb fruits, 20-20 slash gin. To check. Now to copy the 20 twenties directory under the 2019 directory, I will use the d is lowercase or recursive option. To check. As you can see, the gen directory and its contents has been tablet under the 2019 directory. Moving files. The MV Common Dreams files in the same directory or relocates files to a new directory. File contents remain unchanged. Files moved to a different file system require creating a new file by being the source phi, then deleting the source file. Although normally transparent to the user, larger files Meteor noticeably longer time to move. For example, move thickest. Just to check. Here, I used the most common to rename that text file, to test file, and to use the Move command to relocate, that is the pile into the documents directory type. To check. Removing files and directories. Default syntax for the RM command deletes files but not directories, deleting a directory, and the potentiality mini subdirectories and files below, it requires the Daesh or recursive option. There is no command line and delete feature, nor a trash bin for which to restore. For example, to delete the file test in the Documents directory. Or m. Two comments. To check n to delete the 2019 directory and the piles below it, we will need to use the desk or recursive option, or we will get an error. As you can see, our m can't remove 20192019 is a directory. You will try again using the dash or recursive option to check. As you can see after our infile to delete the 2019 directory, that is, our recursive options exceeded. The RM dash R command. Proceed into each subdirectory first, individually deleting contained files before removing each directory. Note that using the dash option with the RM command will interactively prompted for each deletion. This is essentially the opposite of the dish if option, which will force the deletion without prompting the user. The RAM direct comments, deletes directories only if empty. Remove directories can't be on deleted. For example. As you can see, the 20-20 directory isn't empty. If we try the r m dire on it. Here, R M dire comment Phil to delete non-empty 20-20 directory. If we created a new empty directory, 2021 usings amygdala comment and Detroit the r m direct comment on it. To check. As you can see here when deleting the empty 20-20 one directory, the RM dire comments succeeded. I hope this has been informative for you and I'd like to thank you for viewing. 18. 03 Matching File Names Using Path Name Expansion: Matching find names using Beth name expansion file globbing. The bash shell has a birth_name matching capability, historically called the globbing, abbreviated from the global comment fight Beth name Expansion Program of the early unix. The best globbing feature commodity called pattern matching or wildcards, mix managing large numbers of files easier. Using meta characters, also referred to as wildcards. That expense to match file and Beth names being sought. Comments will form on a focused set of files at once. Better-and matching a globin is a shield common parsing operation that expense a wildcard pattern into a list of matching Beth nims. Command line meta characters are replaced by the image list barrier to command execution, but turns especially square bracketed character classes that don't irritate it matches display the original veteran request as literary texts. These are the common meta characters in the veteran classes. You can take a look at them before starting the examples. Assemble set of files is useful to demonstrate expansion. First, create a directory called the globe using the mic dire comment. Make dire glue, and make it the current working directory using the cd command, cd loop. Now, I will create some files starting with different characters using the touch command. Now let's try some examples. First, example of symbol better matches using asterisk. And asterisk matches one or more occurrences of any character, including no character. For example, ls, e asterisk. This will show all files starts with the E Character. Another example. This will show any file includes a in its name. And here, this will show any file starts with the letter E or later. See example of somebody better in matches using question mark. Question mark represents or matches a single occurrence of any character. For example, this command will show all files contains only three characters. And this will show all files contains only four characters in its Nim. Tell the expansion that that character, when followed by a slash delimiter, matches the current user's home directory. And when followed by a string of characters up to a slash. It will be interpreted as a username. If one matches. If new username matches, then an actual tilda followed by the string of characters will be returned. For example, here, tilda represents the bit to the current user's home directory slash home slash MOOC, because it was followed by a slash delimiter. And here, till there represents the bath to the current user's home directory, slash home slash moon, because it was followed by a string of characters matching the username mu. But here an actual tilda followed by the string globe abuse because there was no username matches. Tilda, followed by plus sign expense to the value of the BWT variable, which holds the current working directory until they're followed by a dash sign, expense to the value of the old me WD variable, which holds the oblivious working directory. If all the PWD is unset, delta dash is not expanded. Brace expansion. This expansion is used to generate discretionary strings of characters. Braces contains a comma separated list of strings or a sequence exhibition inside curly braces. A sequence consists of starting and ending items separated by two periods. The result includes the thickest preceding or following the definition. Breeze expansions may be nested one inside another. Let's take some examples. Command substitution. Command substitution allows the output of a common to replace the command itself. Command substitution occurs when a comment is enclosed with a beginning dollar sign and parenthesis, or with bake takes the form with vector x is older and has two disadvantages. First, it can be easy to visually confused back ticks with single quote marks. And second back ticks can be nested inside back ticks. The dollar sign, common form tennis, multiple command expansions inside each other. For example, here I used 10% E for locals full weekday name. And here I used the bursting t to show time is our minutes, seconds. Protecting arguments from expansion. Many characters have special meaning in the Bash shell. To ignore metacharacters, spatial meanings. Single coating and is giving are used to protect them from shell expansion. The backslash is n escape character embellish, predicting the single following character from spatial interpretation. To protect longer character strings, single could is used to enclose strings. Used double quotation marks to suppress globbing expansion, but still allow command and variable substitution. Variable substitution is concept usually identical to comment substitution, but may use optional press syntax. For example, using the single good character with the dollar sign character probe interpretation, meaning that prevented barometer expansion. Using the escape character. Character from interpretation, meaning that it prevented parameter expansion. But here, using the double quotation allowed the dollar sign character to interpret. And here, using the double good prevented Beth Nim expansion globbing. I hope this has been informative for you and I'd like to thank you for viewing. 19. 00 Section Three Overview: Getting help in Linux. This section you will learn heeding the commutation using man command. Sections of the Linux Manual. Sections containing popular system administration topics, identifying mem b, just by keyboard, navigating main beaches. Searching for men business by keyword. The abruptness command, the men DB command, reading documentation using info command, leading Documentation Using the info command. The info path environment variable. Eating recommendation in slash users slash shear sledge doc Directory. Though it is given that this does help option. Getting the graphical help, Vietnam the shell command, the command and the shell built-in commands. 20. 01 Reading Documentation using man Command: Reading the documentation using man command. After completing this lecture, you should be able to locate the communication and the research answers about comments. The historical Linux programmer's manual from which men beaches originate was large enough to be multiple Brinton books, each contained information for specific types of files which have become the sections you see here. Articles are referred to as topics as being just no longer applies. Sections of the Linux manual. Section one for user commands to system calls, three, library functions for special files, H5 file formats, six, games, seven, conventions, standards, and miscellaneous. It, system administration and privilege. It commands N9 Linux kernel application programming interface API to distinguish identical Topic names in different sections. Men BEG differences include the section number in parenthesis after the topic. For example. Thus, would one describes the command to change passwords. While basswood five, explains the sludge, ETC. Slash password file format for storing local user accounts. To read specific main beaches, use men topic that debate contents. Display one screen at a time. You can use the arrow keys for single line scrolling or the space bar for the next screen. The man command searches manual sections in a configured order, displaying tabular sections first, for example, men. Basswood displays best word Section one. By default. You can use arrow keys for single lines crawling or the space bar for the next screen. And you can rescue to exit. To display the men bij for the basswood Command, section five, we will type main five, basswood. Note that reveal our system administration topics are in section one, user comments, section five, file formats, and section it, administrative commands. Administrators using certain troubleshooting tools also use Section two for system calls. The remaining sections are commonly for br, grammar reference or advanced administration. The ability to efficiently search for topics and navigate men beaches is a critical administration scale. Let's try the basic main navigation commands. To open the message of the main command type. Main, main press Space-bar. Scroll forward one screen. Beach down. Also to scroll forward, one is screen Beach up to scroll backward. One screen. Use Down arrow to scroll forward one line. And up arrow to scroll up one line. Press D to scroll forward, 1.5 screen. Pursue. To scroll backward. 1.5 screen. Press forward slash, followed by string to search forward for string in the main beach. Press lowercase in to repeat the previous search forward in the main beach. Our work is in three beats the previous stage backward in the main beach. This lower case g, to go to the start of the main beach. Or Braess. Uppercase G, to go to the end of the main beach. And you can rescue at any time to exit the main beach and returned to the common shell prompt bit. When performing searches inside main beaches. String allows regular expression syntax, while symbol thickest, such as basswood, works as expected. Regular explorations use meta characters such as asterisk, dot, and dollar sign. For more sophisticated, better matching. For example, forward slash O dot t. We'll dot will be replaced with any character. Note that session with strings which include program expression meta characters might yield unexpected results. Session four mm beaches by keyword. A keyword search of name beaches is performed using men. This lowercase key. Followed by the keyword, which displays a list of keyword matching main beach topics with section numbers. For example, main DES key equal. The result here is similar to that of using the appropriate command. Note that keyword searches rely on an index generated by the main DB comment, which must be run as root. The command runs daily through current, the Delhi or boy and a cron tab within an hour of boot if out of date. If men, the ski keyboard command didn't walk with you, try them MDB comment as root first steps for doing this. Switch User two root user. Then enter the main DB comment, followed by Enter. You will need to do this only if the main DES key, keyword comment didn't work with you. To go back to the normal user, you can press Control D, the man command dish, uppercase key, option, performance, a full-text beach fish, not just titles and descriptions like the dish lowercase key option. Note that a full text search can use greater system resources and take more time. For example, main dish, uppercase key, equal. You can rescue, followed by entered to switch between result pages. I hope this has been informative for you and I'd like to thank you for viewing. 21. 02 Reading Documentation using info Command: The info beaches. In addition to the men beaches, you can read the enthalpy just about a command using the info common. This usually contain more recent information and are somewhat easier to use the man pages for some comments referred to the info pages. We will start by typing info in a terminal window. Use the arrow keys to browse through the thickest and move their cursor on a line starting with an asterisk containing the keyboard about which you want info. Then hit Enter. Use the B and N keys to go to the previous or next subject. The spacebar will move you one beach farther. No matter whether the starting a new subject or an info bij for another common. Also, you can use Q to quit. I hope this has been informative for you, and I'd like to thank you for viewing. 22. 03 Reading Documentation using pinfo Command: Reading documentation using VM for comment. After completing this literature, you should be able to research answers using the IOM full recommendation. Be NFO is n info file viewer or a program for viewing info files. The main beaches have a formal format useful as a command reference, but less useful as general documentation. For such documents, they ignore project developed a different online documentation system known as glue NFO. Info documents are an important resource when S intos or it had Enterprise Linux systems because many fundamental components and utilities that are either developed by group project or utilize the info document system. You can specify which base you want to read by basing it as an info beach argument. This argument contains the name of an info Beach. The program will then search for it in the current directory. Slash user slash share sludge in foo directory, and slash user slash local slaves shear slash info directory. The search path can be adjusted by info Beth environment variable in their configuration files, dot profile or don't bash RC files. You can use the info comment only to show that all of the info tree, which is the info topics directory. You can press the right key or the enter key to choose the highlighted topic. Press the left key to go backward. Press D to display the directory of topics, recipes down. What is this? Scroll forward one screen. Brisk Beach up or be to scroll backward. One is clean. Press you to display the parent node of atomic. Press down arrow to scroll forward to nearest hyperlink. Press up arrow to scroll backward to previous hyperlink. Press forward slash, then type string to search for a better. For example, nano. You can rescue at anytime to exit. Info documentation is structured as hyperlinked info notes. This format is more flexible than men beaches, allowing thorough discussion of complex commands and concepts like main beaches, InfoNewt are read from the command line using either the info or b m four commands. Some commands and utilities have both men beaches and info documentation. Usually the info documentation will be more in depth. Now, I will show you the documentation of the PWD command using Men info and be NFO commands. So as you can compare between using any one of them, main PWD, PWD, BM for BWT. The NFO, NFO leader is more advanced than the original info command and designed to match the length sticks to a browser keystrokes. It also adds color. Infonewt is for a particular topic, are browsed with BM photopic. New documentation nodes become available in the NFO when their corresponding software packages are installed. I hope this has been informative for you and I'd like to thank you for viewing. 23. 04 Reading Documentation in /usr/share/doc Directory: Reading documentation in slash users slash shear slash docx directory. After completing this lecture, you should be able to research information using redhead package manager documentation. In addition to main and be NFO, developers may also choose to include documentation in their applications RPM distribution package. The redhead package manager, RBM is N default Open Source and most popular package management utility for redhead based systems like Red Hat, Enterprise Linux centers, and Fedora. This tool allows system administrators and users to install uninstall, query, verify, and managed systems software packages in Linux operating systems. When the package is installed, files recognized as documentation or moved to slash users slash slash docx slash package Nim. Software baggage builders may include anything deemed helpful as accompaniment to but not duplicating main beaches. Blue packages also use slash user slash slash docx directory to supplement info nudes. Most baggages include files describing baggage distribution, licensing. Some packages include extensive PDF or HTML based documentation. Accordingly, ISIL baggage browsing method is pointing a browser of choice. For example, Firefox, two file colon slash user slash slash docx directory to show the index of the dock directory. Some packages come with extensive examples, configuration file templates, Scripts, tutorials, or user guides. Some documentation is sparse. Some packages includes a large user manuals or developer guides or electronic copies of related published books. Note that developers may choose to bundle extensive documentation in a separate RBM. Many packages also include developer documentation, such as an application programming interface specification provided in a package with any ending in Daesh devil or similar. Packages may include additional files such as headers. Useful documentation usually only needed for software development or combining. I hope this has been informative for you and I'd like to thank you for viewing. 24. 05 whatis command: The other is common. A short index of explanations for commands is available using the art is common, as in this example. What is Ls? These displays shortly information about the common. And the first section in the collection of men beaches that contains an appropriate beach. I hope this has been informative for you and I'd like to thank you for viewing. 25. 06 --help option: The dash dash help option was to glue commands abort the dash dash help option, which gives a short explanation about how to use the comment and the list of available options. Let's try this option with the cat common ket, dash, dash help. As you can see, it gives a short explanation about how to use the cat command and a list of its available options. I hope this has been informative for you. And I'd like to thank you for viewing. 26. 07 Linux Graphical Help: The graphical help. Don't despair if you prefer a graphical user interface. The genome helping browser is very user-friendly and it provides painless access to the main and info pages where the system documentation at main beaches are easily browsable with Abilene interface. You can start it by entering the comment genome, dish help info, colon, NFO, or by typing yell NFO, colon info. And you'll get a browsable info Beach about the info command. Similarly, yellow main column. Ls, will present you with the main beach for the ls command. Note that some coins don't have separate documentation because the orbits of another comment, such as CD, exit and look out. The birth of your shell program and are called shell belt and commands. I hope this has been informative for you and I'd like to thank you for viewing. 27. 00 Section Four Overview: In this section, you will learn creating, viewing, and editing text files in Linux, which will include describing the technical term is standard input, standard output, and standard error. Using the read direction characters to control output two files. Using byebug to control output to other programs. Creating new files and editing existing text files from the shell prompt bit navigating within an editor to effectively accomplish editing tasks. Using the editor in The basic editing tasks. Editing text files with g edit, copying thickest between graphical windows. 28. 01 The touch command: The touch command is a standard program for Linux operating systems and that is used to create, change and modify timestamps of a file. Let's take some examples of using the attach command to create an empty file test. You can use the command and to check to change or update the list xs and modification time of the file data, you can use the best option. For example, to check. Here, I used the option to solve list x time instead of lust modification type. Using the risky options hits the current time. Indeed, when a file here, if the data file doesn't exist, it will create a new empty PI data. To avoid creating a new file, you can use the dashed c option, for example. To check. This command will not create the file if it doesn't exist. If you'd like to change only the modification time of the file test, then you can use that as an option. For example, to check node, it will only update the lost modification time of the test file and the access time will remain as it is. The touch command can also connect any number of files simultaneously. For example, to create three new empty files named pi one, pi two, and pi three, you can use the command to check. Thanks for viewing. 29. 02 Redirecting Output to a File or Program: You directing output to a file or program. After completing this ligature, you should be able to describe the technical terms, standard input, standard output, and standard error. Use redirection characters to control output to files and use by being to control output to other programs. A process is structure, is constructed with number two channels called file descriptors to manage urban files. Processes connect two files to reach data content or devices. These files represent. Processes are created with default connections for the channels 012, known as standard input, standard output, and standard error. Processes use the channel three and above to connect to other files. January direction replaces default channel destinations with filenames representing either output files or devices. Using the detection process, output and error messages can be captured as file contents sent to a device or discarded. The directing standard output suppresses roses output from appearing on the terminal. As seen in this example. We directing only standard output doesn't suppress standard error messages from displaying on two-terminal special file sledge dip national quietly discards channel outwardly directed to it, as in this example, when redirecting the standard error. Note that the previous commands will override or event the existing file or create a new file if the file is not existing, the order of redirection is important to avoid unexpected command behavior. Using the command to redirection operator ampersand one, send this the standard error to the simplest as standard output. For this to work, standard out needs to be redirected fairest before adding standard error to standard output. Although using the comment ampersand followed by the abundant operator is an alternate way to append both standard out and standard error to a file using the command to redirection operator ampersand one is the method needed to send both standard output and standard error through a pipe. Let's take some examples for output redirection. Mini routine administration tasks are simplified by using redirection. Use the previous table to assist while considering the coming examples. The first example is receiving a timestamp for literary reference. Here we will use the date command, followed by the redirection operator, followed by the Beth, followed by the filename. For example, timestamp. We can inject using the cat command. Another example, to copy the last 100 lines from a file to another file. First, I will need to switch to root user using the SQL command, followed by the redirection operator, followed by the filename. To check. You can breastfeed for autocompletion. To concatenate three files into one file. First, I will need to create three files using the touch command in the sludge TMP directory. To check. Then I will add some data in each file using the echo command and redirection operator. Then you can check the data entered in the files using the cat command. Now to concatenate the three files into one file. To check for listing the home directory is hidden and regular file names into a file. First, you will need to ensure that you are in the home directory. We can check the tilda sign. And if you are in a different one, you can use the command cd space tilda to switch to the home directory. Now to lead to the home directory is hidden and regular file names into a file. And to check another example to obtain the output and the date command to the existing file timestamp using the append operator. For the coming example, we will first need to switch to normal user. You can use Control D. In this example, arrows are generated since normal users are denied access to system directories to re, direct heirs to a file while viewing normal command output on the terminal, I used the command two, followed by the redirection operator, followed by the Aerospike. To check into sieve, process output and error messages to separate files, we will use this comment. And to check to ignore and discard error messages. We can relate it to sludge div slash null to store output and generated arrows together, we can use the command ampersand, followed by the redirection operator, like in this example. And to obtain the output engine rated errors to an existing file. To check, all you can use ampersand followed by the append operator, followed by the filename. Constructing pipelines. You, David Chang controls channel output to or from files, while by being sends channel output to another process. Let's take some examples. To Maginot Ottomans long outward by binding it to list comment, type. By less. List is a program that allows backward and forward movement in the file. You can do this using Beach down and beach up all the space bar. Also, it doesn't have to read the entire input file before starting. So with large input files, it starts up faster than text editors. You can press q to quit. In this example, we used the dash l option for long listing form it. Another example to count the number of lines in an output or listing type. The option is used with the word count command to brand the newline counts. Now to check versus input and output vibing with T comment that he commands lays all the directories, the intermediate results normally suppressed due to by being. Let's take some examples. In this example, the LS listing is viewed on the terminal while simultaneously being stored in a file. I hope this has been informative for you and I'd like to thank you for viewing. 30. 03 Editing Text Files from the Shell Prompt: Editing text files from the shell prompt. But after completing this lecture, you should be able to create new files and edit existing text files from the shell prompt bit, navigate within an editor to effectively accomplish editing tasks. Use the editor in The basic editing tasks. A key design principle of Linux is that information is stored in text files. Text files include both flat files with rows of similar information, such as configuration files in sludge, ETC. Directory. And extensible markup language files which define data structure through text, takes scene in application configuration files throughout both slash, ETC, slash user directories. The advantage of thickest files is that they can be moved or shared between systems without requiring conversion and can be viewed and edited using any symbol text editor. The editor is an improved version of the VI editor distributed with Linux and Unix systems. It is the most popular and classic text editor in the Linux family. Highly configurable and efficient for breakfast users. Including features as split-screen editing, color formatting, and highlighting, or editing text. When you open them, it started in command mood, used for navigation, cut-and-paste, and other text manipulation. You can enter each of the other moods with single character keystrokes to access a specific editing functionality. And icky stroke enters, insert mood. We're all takes type KMZ file, content. Pressing, Escape, bitterness to command mood. At vk keystroke enters visual mood where multiple characters may be selected for tickets manipulation. You can use V for multi-line and Control V, four block selection. The same keystroke used to enter visual mood. Uppercase V, lowercase v, or control V, is also used to exit. The column keystroke begins extended command mode for tasks like writing the file to save it and equating the Vim editor by following it with characters like Q or WQ or others according to what you want to do. For example, colon q will exit without saving. And colon WQ, we'll save and exit. Let's take a look at the basic Vim workflow. The basic BIM workflows presents the minimum keystrokes every Vim user must learn to accomplish any editing task to open a file with them. Type vim, followed by the filename. It's important to not forget the space between them and the file name. Then press enter. After opening the file. If the file you open contains data, you can use are keys to position the cursor. You can press the icky to enter the insert mood. Now you can add new tickets to the file or edit the existing. Risk skip to return to command mode. You can pursue to undo mistaken edits on the current line. And you can press control are to redo. Also you can best X to delete a selection of texts. To save or exit, choose one of the following two, right or discard file edits. You can enter colon w, followed by Enter to save the file and remain in command mood for more editing. Or colon WQ, followed by Enter to write the file and duckweed Vim, or q exclamation mark followed by Enter to quit vim, but discard all file. It changes since the last trite. In them, cabbie and Beast is known as Yank and boot. Using command characters y and b. Begin by positioning the cursor on the first character to be selected. Then enter visual mode by pressing V. Use our keys to expand the visual selection. When Lady press Y to yank this election into memory. Position the cursor at the new location. Then press B to both desolation at the cursor. Now, to quit vim and discard the changes. Press escape, enter the command mood. Then type colon q, exclamation mark, and press enter. Beware that then requires practice to become efficient, it is recommended to continue learning new keystrokes to extend bends usefulness. For those curious how extensive this can be performed. An internet search for Vim tips. Also, you can use the Vim tutor to learn your first Vim commands, which is a 30-minute tutorial that teaches you the most basic Vim functionality in it. Easy exercises. While you can't learn everything about them in just half an hour, the tutor is designed to describe enough of the commands that you will be able to easily use them as n, all Berbers editor. You can start this program from the shell or command line by entering the vent tutor command. This will make a copy of the tutor file so that you can edit it without the risk of damaging the original. There are few translated versions of the tutor to find out if yours is available. Use the two litre language could, for example, for French, this would be them tutor FOR IF installed on the system. I hope this has been informative for you and I'd like to thank you for viewing. 31. 04 Editing Text Files with a Graphical Editor: Editing text files with a graphical editor. After completing this lecture, you should be able to edit text files with g edit cabbie tickets between graphical windows. The g edit application is a full featured text editor for the gnome desktop environment. You can lunch g edit by selecting activities. Show applications. All text editor. Also. Like other graphical applications, g edit can be started without navigating the menu. Press F2. To open the enter a comment dialogue box, then type g edit and press enter. You can perform many file management tasks using g edit menu hits first, enter some data in the document. To create a new file in g edit. Click the blank paper toolbar icon, which will create a new document in a separate tab within the same window. Or from the text editor menu. Select New Document. And to open a new document in a separate window, you can press the thickest editor button and choose UN do. Or you can press Control N, which will also create a new document in a separate window. To save a file. You can click the Save button. Then type the new file name or confirmed the current by clicking the Save button. Or from this button. Select Save As or save all. Also, you can easily press control S to save the file. To open an existing file. Click the oven toolbar button. Then click on the other documents poten. The Open Files dialog window will display from which users can locate and select the file to open. Multiple files may be open simultaneously, each with a unique tab under the menu bar. Tabs will display the filename after being saved the first time. Being tickets between graphical windows. Text can be carried between documents, thickest windows and command windows in the graphical environment. Selected, thickest is duplicated using cabbie and Beast or moved using cut and beast. With our cut or carried. The thickest is held in memory for pasting into another location. To select thickest. Click and hold the left mouse button before the first character desired. Drag the mouse over and down until all required to guest is in a single highlighted selection. Then release the left button. Don't click again with the left bottom as that deselected that text. To boost the selection, multiple methods can accomplish the same result. In the first method, click the right mouse button anywhere on the text areas just selected. From the resulting context menu. Select either cut or cabbie. Move the mouse to the window or document. Where did that text is to be placed? Click the left mouse button to position. Where did that it should go. Click the right mouse button again. Nail choosing pissed. A short-term mouse technique is to first select the biggest. Hover, the mouse over the destination window. And click the center mouse button just once to bestow the thickest at the cursor. Note that this method can only cabbie not cut, end the original ticket strumming selected and can be deleted. As with other methods, the thickest remains in memory and can be repeatedly bested. The keyboard shortcut method can also be used in graphical applications. First, select that a guest. Use Control X to cut or Control-C to copy the thickest. Click the location where the thickest is to be blessed to position the cursor. Then click Control V two beast. Note that control c and control v will not copy and paste within a terminal window. And that control C will actually terminate the current running process within a terminal window. To copy and paste within a terminal window. You can use control shift C to copy and control shift V two beast. I hope this has been informative for you and I'd like to thank you for viewing. 32. 00 Section Five Overview: 609 overview, managing local Linux users and groups. In this section, you will learn what a multiuser system is using the id command, using the BS command, the sludge, ETC. Slash password file. What a group is. The sludge ETC. Slash Group file. The primary groups, the supplementary groups. What a root user is, switching users with the SU command, running commands as root. With this you do commend the sludge, ETC. Slash, see you doers file. The group wheel, the policy kit. Managing local users, the user edX command, the sludge, ETC. Slash login dot d fs file. The user mood command, the user del, command, the id command, the best route command. The user id ranges. Managing supplementary groups. The group Ed command, group mode Command, the group del command, the user mode, comment, shadow buzzwords, and Bedford policy, the sludge, ETC, slash shadow file. The select command, password, ageing, the change each command. Using the date command to calculate a date in the future, restricting access. The normal again shell. 33. 01 Linux Users and Groups: Linux users and groups. After completing this lecture, you should be able to explain the role of users and groups on a Linux system and how they are understood by the computer. The next is a multi-user system. And operating system is considered multi-user if it allows multiple people to use a computer and not affect each other's stuff like files and preferences. Every process which is running programs on the system runs as a particular user, and every file is owned by a particular user. Accessing to files and directories are restricted by user. And the user associated with a running process determines that the files and directories accessible to that process. You can use the id command to show information about the current logged in user. As you can see here, it shows the UID, which is the user ID, and GID, which is the group ID and the groups for the current user. Basic information about another user can also be requested by basing in their user name of that user is the first argument to the ID command. For example, to view the user associated with a file or directory. You can use the ls dash l comment. Like here. The animals file is associated with the user and statistic group. The fields displayed here represents file permissions, number of links, the owner name, the group name, the file size, the time of last modification, and the file or the directory name. File permissions are displayed as following. First character is dish or L, or D. A dash represents a file. D indicates a directory, and L is a symbolic link or softly, followed by three sets of characters three times, indicating permissions for owner, group and the other. R means readable and W writable and executable. To view process information, you can use the BS comment. The default is to show only processes in the current shell. And we can use the option to view all processes with a terminal. To view the user associated with a process include the u option. The first column shows the username. The output of the previous commands displays users by name. But internally, the operating system takes users by a user ID, you ID number. The mapping of names to numbers is defined in databases of account information. By default, systems use the sludge, ETC. Slash password file to store information about local users. The format of the sludge, ETC. Slash password file follows seven colon separated fields. The first field is for the username, the second for the password, the third for the user ID, the fourth for the group ID, the fifth for the G equals field, six for the user home directory, and seven for the shell used. The first field username is a mapping of a user ID to an aim for the benefit of human users. The second field, password, is where historically passwords were kept in an encrypted form it today they are stored in a separate file, sludge, ETC, slash shadow. The third field, user ID is a number that identifies the user at the most fundamental level. The fourth field, Group ID, in the user's primary group ID number. The fifth field, glucose, is typically used to record the general information about the account or its user, such as the users real name and phone number. The sixth field, slash home slash username, is the location of the user's personal data and the configuration files. And the seventh field, sludge spins less fish, is a program that runs as the user logs in. For a regular user, this is normally the program that provides the user's common line Brom bit. What is a group in Linux? The next groups are a mechanism to manage a collection of computer system users. Like users, Linux groups have an M and a number, which is a group ID. Local groups are defined in slash slash Group file. Primary groups. Every user has exactly one bribery group for local users, the primary group is defined by the group ID number of the group listed in the fourth field of the sludge, ETC, slash password file. Normally the bribery group owns new files created by the user. And normally the primary group of a newly created user is a newly created group with the same name as the user, and the user is the only member of this user private group, supplementary groups. Users may be a member of 0 or more supplementary groups. Users that are sedimentary members of local groups are listed in the last field of the group's intrigue in the sludge sludge Group file. For local groups, user membership is determined by a comma separated list of users found in the last field of the group's entry in the sludge sludge group file. Supplementary group membership is used to help ensure that users have access permissions to files and other resources on the system. I hope this has been informative for you and I'd like to thank you for viewing. 34. 02 Gaining Superuser Access: Gaining superuser access. After completing this lecture, you should be able to run commands as the superuser to administer a Linux system. Most operating systems have some sort of super user or users that has all power over the system. This user is the root user. He has the power to override normal privileges on the file system and is used to manage and administer the system in order to perform tasks such as installing or moving software and to manage system files and directories, I user must escalate privileges to the root user. Most devices can only be controlled by root, but there are a few exceptions. For instance, removable devices, such as USB devices, are allowed to be controlled by a normal user. Thus, a nonroot user is allowed to add and remove files and otherwise managed a removable device, but only root is allowed to manage or fixed hard drives by default, this unlimited privilege, however, comes with responsibility. The root user has unlimited power to damage the system, like remove any pies and directory's, removing user accounts, adding backdoors and others. If the root account is compromised, someone else would have administrative control on the system throughout the course, administrators will be encouraged to walk in as a normal user and escape privileges to root only when needed. The root account on Linux is roughly equivalent to the local administrator account when Windows. Note that most system administrators like into an umbrella user account and use various tools to temporarily gain root privileges like Switch User, C, u du, or bossy kit. By logging in as the administrative user, the entire desktop environment unnecessarily runs with administrative privileges. In that situation, in a security vulnerability which would only compromise the user account has the potential to compromise with the entire system. In recent versions of Microsoft Windows, administrator disabled by default in features such as a user account control are used to limit administrative privileges for users until actually needed. In Linux WC kit system, if the newest equivalent to user account control. Switching users with the Switch User command. The SU comment allows a user to switch to a different user account. If a username is not specified, the root account isn't blind. When invoked as a regular user, type SU two switch to the root user, followed by enter. A Brahmin display asking for the password of the account you are switching to. When invoked as root to switch to move user type ASU, followed by the username, and press enter. Here. There is no need to enter the account password as you are switching from the root user account. The comment is you followed by username, started and unplugging shell. Why did the command ESU space, this space test starts elegant shell. The main difference between using the command is u and using the command is u, space dish. Here we use the command SU space dish to switch to the root user, followed by inter. Here, as you can see, using the command is used. Space dish sets up the shell environment as if this were a clean login. Is that user, while using the comment, is you only just starts a shell as that user with the current environment settings. In most cases, administrators want to run the comment is you space dish to get the user's normal settings node that the SU command is most frequently used to get a command line interface which is running, is another user typically route. However, with the dash c option, it can be used like the Windows utility run to run an arbitrary program is another user. For example, to show the sludge sludge pseudowords file, you can use the command running commands as root. With this, you do comment. Fundamentally, the next implements a very restricted permissions model. Group can do everything, other users can do nothing pull systems related tasks. The common solution previously discussed is to allow standard users to temporarily become routes using the Switch User command. The disadvantage is that while acting as route, all the privileges and responsibilities of routes are granted. Not only can the user restart the observer, but they can also remove the entire sludge, ETC, directory. Additionally, all users requiring superuser privilege in this manner must know the root password. The sudo command allows a user to be permitted to run a command as root or as another user based on settings in the sludge, ETC. Slash pseudowords file. Unlike other tools such as Switch User C, you do requires users to enter their own buzzword for authentication, note the password of the account they are really trying to access. This allows an administrator to hand out fine-grained permissions to users to dedicate system administration tasks without having to hand out the root password. For example, when CO2 has been configured to allow the user to run the command user mode as root MOOC could run the following command to lack a user account. As the user move is not allowed to run this command as root and the user is not in the doers file. Locking the user account test has failed. The easiest way to give a user pseudo access without modifying your servers you do ours file is to use the user mode common to aid the user to the wheel Group, for example. And to check. And to make the group, we see that the primary group for the user MOOC, we will need to use the dish lowercase g option. And to check, we can check using the command. Let's try again looking user accounts. User accounts that succeeded. If we try to switch user to user account. As you can see, the authentication failure. Now, the test user account is logged. Also, you can use the best food command to lock, unlock, reject the status of a user account. You can use this lowercase L to lack the user account. Dish lowercase u to unlock the user account. And this our keys is to check the status of a user account. Now, let's check the status of the test user account. Note that only root can use this command. End to unlock the dist user account. Type that command. As you can see, the unlocking succeeded. Now let's try to switch to the test user account. As you can see, the switching succeeded. One additional benefit to using pseudo Is that all commands executed using pseudo are lagged by default to sledge bored slash, slash secure file. In Red Hat Enterprise Linux seven and up hold members of group. We'll can use Tudou trunk commands as in user, including route. The user will be prompted for their own buzzword. This is a change from Red Hat Enterprise length six and ealier users who we're members of group, we didn't get this administrative access by default, ended HIT enterprise leg sex. And earlier. As you can see, this line in this Eudora despite allows people in group. We'll run all commands. Load that it had. Enterprise Linux six didn't grant group we in special privileges by default. Sites which have been using this group may be surprised when Red Hat Enterprise Linux automatically grants all members of full sudo privileges. This could lead to unauthorized users getting superuser access to Red Hat Enterprise Linux systems. Historically, membership in group wheel has been used by Unix-like systems to prevent or control superuser access. Most System Administration applications with a GUI US policy Kate to prompt users for authentication and to manage root access. It, it had Enterprise Linux seven and up policy kit may also prompted members of groups for their own buzzword in order to get root privileges when using graphical tools. This is similar to the way in which they can lose you do to get those privileges at the shell Brahmins policy get grants these privileges based on its point configuration settings separate from CO2. Thanks for viewing. 35. 03 Managing Local User Accounts: Managing local user accounts. After completing this lecture, you should be able to create, modify, luck, and lead locally defined user accounts. And number of command line tools can be used to manage local user accounts. First, they user add comment. Linux is a multi-user system, which means that more than one person can interact with the system at the same time. As a system administrator, you have the responsibility to manage the system's users and groups by creating and removing users and assign them to different groups. In Linux, you can create a user account and assign the user to different groups using the user add command. For example. To use the user add comment. First, you will need to switch to the root user. Then type user ID, followed by the new username. For example, Thera. This sits reasonable defaults for all fields in sludge, ETC. Slash password file when run without options. To check. It doesn't sit in invalid password by default. And only the root user can login and password is set. To set Sarah user password. You can use the command. You can use the user eight dash, dash help option to display the basic options that can be used to overwrite the default. In most cases, the same options can be used with the user mode comment to modify an existing user. The slash slash login dot d fs phi. Some defaults such as the default password, ageing rules and the range of valid user ID numbers are read from the sludge, ETC. Slash login dot DFS file. Values in this file are only used when creating new users. A change to this file will not have an effect on any existing users. The user mode Command and Linux distributions. The command user mode is used to modify or change any attributes of n already created user account via command line. Such as change user's home directory, login name, login, shell, password, expiry date, or others. It is similar to the user aid or edX user commands, but the login granted to an existing user. Only the user root is allowed to execute user mode comment. When we execute the User Mode command in terminal, the following files are used and affected. Slash slash password file, producer account information, shadow file for secure account information. And only the root user control this file. This file contains the user's passwords, sludge, ETC. Slash Group file for group account information. Shadow file for secure group account information. Lagging, DFS file, core shadow passwords, sweet configuration. As we said before, you can use the user mode dash, dash l option to display the basic options that can be used to modify an account. Determine user mode comment options include that this e option is used with the dish uppercase G option to append the user to the supplemental groups mentioned without removing the user from other groups that they see comment option to add a value such as a filename to the field. The DSD home directory option to specify a new home directory for the user account. That this g group option specified the primary group for the user accounts. The dish uppercase G groups option specified a list of supplementary groups for the user account. The dish uppercase L lack option to lack a user account. The dish em, move home, option to move a user home directory to a new location must be used with the HD option. The dish S Shell option, to specify a new ligand shell for the user account. And the dish uppercase you unlock option to unlock a user account. For example, to sit a brief comment about the user account using the dish C option. Now to check. Let's take another example for setting the user test account expiry date using this option before setting up an expiry date on the user test. Let's first check that this account expired status using the change is command to change it to first engineering 20-25, using the user mood command. To check the user dealt comment. The user dealt command is used to delete a user account and the related files. This command basically modifies the system account files, deleting all the interests which referred to the username login. It is a low-level utility for removing the users. It removes it the user from the sludge, ETC, slash password file, but leaves the home directory intact by default, you can use the user's username command to remove the user and the user's home directory. For example. To remove the user folks and his home directory. To check node that when a user is removed with the user del comment without the dish, are options specified? The system will have the files that are owned boy, and an assigned user ID number. This can also happen when files created by a deleted user exists outside the home directory. This situation can lead to information leakage and other security issues. And it had Enterprise Linux seven and up, the user add command assigns new users the first free user ID number available in the range starting from user ID 11000 or above. Unless one is explicitly specified with the Des you user ID option. Have the information leakage can occur if the first Fi user ID number had been previously assigned to a user account which has since been removed from the system. The old user's user ID number will get assigned to the new user, giving the new user ownership of the old users or meaning files. This scenario demonstrates this situation. If we added a new user and you home directory will be created for SEM. And if we deleted the user same without adding the desk or option, the home directory of the user same will remain as it is. Notice that when we created a new user, Yara, and here user ID become the same user ID that Sam was taking you around now owns all files that Sam once owned. Depending on the situation, you can do the following to get rid of all of the user's files. First, you can delete the removed user's home directory using the RM dash R username comment. For example, to remove same home directory. Note that if you are in the home directory, you don't need to specify the full path to same. You can type them directly. Heave, you need to tie BS for every file in the directory. Same. Instead of this, you can press control C to exit that they're moving to the comment to force the deletion without asking to check. The second way, you can find an own files and directories by running the command. Then you can delete every file in the output of the previous command using the RAM comment. The id command. The id command is used to display user information, including the user's ID number and the group membership. Using the ID username command will display user information for username, including the user's ID number and the group membership. For example. The best would command. The best word Username command can be used to either set the user's initial password origins, that user's password. If used without specifying username, it will prompt for changing the current user password. The root user can set a password to any value. For example, to set a password for the user Sarah. And I said you will be displayed with a password doesn't meet the minimum recommended criteria, but it's followed by a drumbeat to retype the new buzzword and all tokens are updated successfully. A regular user must choose a password which is at least eight characters in length and is not based on a dictionary reward, the username or the oblivious buzzword. The user ID to interests specific user ID numbers and ranges of numbers are used for specific purposes. Weighted head Enterprise Linux, user ID 0 is always assigned to the super user account. Root. User id one to 200 is the range of system users are saying aesthetically to system processes weighted head for internal IT head system user accounts, files and directories can be owned by these accounts. User ID to a 101 to 999 is a range of system users used by system processes that don't own files on the file system. They ultimately assigned dynamically from the available pool with the software that needed them is installed. Brooklyn's R1 is these under-privileged system users, in order to limit their access to just the resources they need to function. User ID when 1000 and above if the range available for assignment two regular users. Note that prior to Red Hat Enterprise Linux seven, the Convention would that user id one to 499 was used for system users and user id 500 and above for regular users. Default read just used by user ID and group. It can be changed in the sludge, ETC. Slash login dot DFS phi 36. 04 Managing Local Group Accounts: Managing the local group accounts. After completing this lecture, you should be able to create, modify, and lead locally defined group accounts. Managing supplementary groups. A group must exist before a user can be added to that group. Several command line tools are used to manage local group accounts. The group add comment. The group ed group name command without options uses the next available Group ID from the range is specified in the slash slash login dot DFS pile. As you can see here, the group ID minimum number is 10000 and the group ID maximum number is 60 thousand. Note that you can use the group. This group ID command specifying a specific group ID. For example, to add a new group by phone with a Group ID 2 thousand. To check. Note that given the automatic creation of user Brexit groups, that takes group ID 1000 and above is generally recommended to set aside a range of group ID numbers to be used for supplementary groups. High range will avoid a collision with assessment group group ID from 0 to 999. Using the dash R option with the group add comment will create assistant group using a Group ID from the range of valid system group ID numbers listed in the sludge. It is eat slash login dot d fs file. For example, to add a system group Java users. To check. As you can see, the Java users group ID is 974 in the range between 0999. The group not comment. The group not command is used to change a group name to a group ID mapping. You can use that as an option to specify a new name. For example, to change the group name Java uses to Java app to check. And you can use the option to specify a new group ID. For example, to change the biofilm group group ID to 5 thousand. And to check the group didn't comment. You can use the tail command to remove a group, for example, to move the Java App group. Here I used the grep command to select Java app from the group file. If exist, is there is no result, then Java is deleted successfully. Knew that a group may not be removed. If it is the primary group of any existing user is with user, then Comment. Check all file systems to ensure that no file zoom-in owned by the group. The user mode comment. The membership of a group is controlled with user management. You cannot change a user's brain regroup with the user moves the z group name command. For example, to make the group move the bribery group for the test user. And to check. And you can add a user to a supplementary group with a user mood. This EA, uppercase G, group name, username comment. For example, to add the user test to a supplementary group. And to check. Here, the use of the option is to make user mode function in the mood. Without it, the user would be removed from all other supplementary groups. I hope this has been informative for you and I'd like to thank you for viewing. 37. 05 Managing User Passwords: Managing user buzzwords. After completing this lecture, you should be able to lack accounts manually or by sitting a buzzword easing policy in the shadow password file. Shadow buzzwords and password policy. In the distant past, encrypted passwords were restored in the audit, readable sludge, ETC, slash password file. This was thought to be reasonably secure until dictionary attacks on encrypted passwords became common. At that point, the encrypted passwords or password hashes will move to the more secure sludge, ETC, slash shadow file. This new file also allowed buzzword aging and explaination features to be implemented. There are three pieces of information stored in a modern buzzword hash. The ID, the salt, and the encrypted hash. The first part is the hashing algorithm. The number six indicates a secure hash algorithm. 512 is used. Number five indicates a secure hash algorithm to a 156 is used. And number one, I beams when an MD5 hash is used. The second board is the salt used to encrypt the hash. This is originally choosing at random. The salt and the unencrypted buzzwords are combined and encrypted to create the encrypted password hash, which is the third board. The use of assault prevents two users with the same password from having identical interests in the sludge, ETC. Slash shadow phi. And the third birth, if the encrypted hash. When a user tries to log in, the system looks up the entry for the user in the sludge, ETC. Slash shadow file combines the salt for the user with the unencrypted password that was tied in and encrypted them using the hashing algorithm specified. If there isn't matches the encrypted hash the user typed in the right password. If the result doesn't match the encrypted hash, the user typed in the wrong password and the login at ten bit fields. This method allows the system to determine if the user typed in the correct password without storing that buzzword in a form usable for logging in. With that Enterprise Linux aboard to strong password hashing algorithms, secure hash algorithm to a 156 Algorithm five and thicker hash algorithm by a 112 algorithm six, both of the salt string and the encrypted hedge or longer for these algorithms. Red Hat Enterprise Linux, it and centers, it defaults to using secure hash algorithm by a 100 and twelv encryption. You can check using the sludge, ETC. Slash, select sledge system, dish, oath file or sludge, ETC. Stage Select slash buzzword niche. Using the command. Both select, test IS both Select is a utility that simplifies the configuration of user authentication on edit head Enterprise Linux host. The popular options that you can use with this command. Dash e to print the content of all files. Dhs to break the password file content. And this b, also to bring the best word Daesh file content. It is eat less shadow file format. The format of the sludge, ETC. Slash shadow file follows nine colon separated fields. First field, mean. Second. Third, plus the change. The fourth, minimum edge. Fifth, maximum age. The sixth. The seventh, inactive. Ate expired. And the last Plank. The first field nim, is the login name and Must be a valid account name on the system. Second buzzword is the encrypted password and password field, which starts with an exclamation mark, means that the buzzword is loved. Third, last exchange is the date of the last password change, represented as the number of days since January 19, 74th minimum edge is the minimum number of days before a buzzword may be changing, where 0 means no minimum age requirements. Fifth, max age. Is the maximum number of days before a buzzword must be changed. Sixth, warning is the owning barrier. That password is about to expire, represented in days where 0 means no warning given. Seventh, inactive is the number of days and account means active after a password has expired, I user mister luck into the system and they change the buzzword during this period. After the specified number of days, that count is lagged, becoming inactive. It expire is the account exploration did represented as the number of days since first January 19, 79th. Blank is blank field that is reserved for future use. Password eating. This diagram relates the relevant buzzword imaging parameters which can be adjusted using the change is common to implement a buzzword aging policy. Let's take some examples. Using the change is DSD 0 username command will force a buzzword update on next login. For example. Now let's try to switch user to Judy. You are required to change your password immediately. Administrator enforcement. You can use the change is this username command to list a usernames current settings, for example. Another example. You can use the change is this uppercase 0s, followed by eight years. This month, Daesh days command to expire and account on a specific day, for example. And to check using the dead comment to calculate a date in the future. You can use the date command to calculate it in the future. For example. Here we use this command to 845 days to the current date. Restricting xs is command an account exploration can be set. Once that did, the user can't log into the system interactively. You can use the User Mode command to lock an account with the dish, our keys option, for example, to luck Tom, account, to check. And you can use the user mode, this upper case u username comment to unlock the user account. For example, to unlock their user account, and to check. Another example. When a user has lifted, accompany the administrator me luck and xbar and account with a single user mode comment, that it must be given as the number of days since January first 1970. This is done using the dish e option, followed by the number of days since January first 1970. To check. As you can see, when added 1D to January first 1970, January second 1970. Or instead of the number of days since January first 1970, you can add the date of expired year, dash month, dash D, for example. And to check, lacking the account prevents the user from authenticating with a password to the system. It is the recommended method of preventing access to an account by an employee who has left the company. If the employee returns, the account can literally be a lagged with the user mode, this uppercase you username comment. And if the account was also expired, be sure to also change the explanation. Did the NO ligand shell. As a system administrator, you will inevitably perform shuttle system maintenance is at some point or another a few times, your system may also encounter some problems and you will be forced to vote it down to fix the problems. Whatever the situations is. It is a good idea to prevent regular users from connecting to the system. Another situation is that sometimes I user needs an account with a password to authenticate, to assist them, but doesn't need an interactive shell on the system. For example, a mail server may require an account to store meal and password for the user to authenticate with Emil client used to retrieve meal. That user doesn't need to look directly into the system. A common solution to these situations is to set the user's login shell to the sludge is spin. No login file. If the user attempts to log into the system directly, the NO ligand shell will simply close the connection. For example, to set the user's desk lagging shell to the sludge Spin slash no login file. Now let's try switching user to the user test. As you can see, setting the user test login shell to the sludge Spin slash no login file succeeded. Mood that instead of the user mode is command, you can use the dish command. Or you can simply open the sludge less basswood file using any of your favorite command line text editors like them or nano, and change a specific user shell. For example. To switch, that is user shell to slash bin slash bash. First we will need to enter the insert mood by pressing the in-breath escaped to enter the command mode. Type column WQ to save and exit, followed by Enter. Now let's try to switch to the user test. As you can see, switching succeeded. Note that use of the normal ageing shell prevents interactive news of the system, but doesn't prevent all X's. Ie user may still be able to authenticate and upload already tried files through applications, such as with applications, file transfer programs, or mid leaders. I hope this has been informative for you and I'd like to thank you for viewing. 38. 00 Section Six Overview: Controlling access to files with Linux file system permissions, section overview. The section goal is to set Linux file system permissions on files and interpret the security effects of different permission settings. After completing this section, you should be able to explain how the Linux file permissions model walks. Change the permissions and ownership of files using command line tools. Configure a directory in which newly created files are automatically writeable by members of the group which owns the directory. And using the special permissions and default you mask settings. In this section you will learn Linux file system permissions effect is of permissions on files and directories. Viewing file and directory permissions and ownership. What the security enhancing Linux is. Practical examples of controlling permissions and they're allowed and denied Behavior. Managing file system permissions from the command line. Changing file and directory permissions. The symbolic method keywords. The numeric method. Practical examples of controlling permissions using the symbolic and the numeric methods. Changing file and directory user or group ownership. The change owner comment, the Change Group comment, managing default permissions and file access. Michele permissions, the user ID permission, the set group ID permission. The sticky bit permission effect is of special permissions on files and directories. Sitting special permissions, default file permissions. The UMass command. And practical examples of using the UMass command. 39. 01 Linux File System Permissions: Linux file system permissions. After completing this lecture, you should be able to explain how the Linux file permissions model works. Linux file system permissions, access to files by users is controlled by file permissions. The Linux file permission system is symbol but flexible, which makes it easy to understand and apply yet able to handle most normal permission cases easily. Files have just three categories of user to which permissions apply. The file is owned by a user, normally the one who created the file. The file is also owned by a single group, usually the primary group of the user who created the file. But this can be changed with different permissions can be said for the owning user, the owning group, and for all other users on the system that are not the user or a member of the owning group. The most specific permissions are blowing. So user permissions, verite group permissions, which override other permissions. In this graphic, Sam is a member of the group Sam and Python. While Tom is a member of Tom will and biotin groups. When Sam and Tom have the need to collaborate, the files should be associated with the group Python, and the group permissions should allow the desired access. There are also just three categories of permissions which apply, read, write, and execute. These permissions affect access to files and directories as follow. When applying the read permission, the contents of the file can be read and contents of the directory can be listed. When applying the write permission. Contents of the file can be changed. And INI file in the directory may be created or deleted. And the when applying the execute permission, files can be executed as commands and contents of the directory can be accessed. And this is depending on the permissions of the files in the directory. Note that users normally have both read and execute a read only directories so that they can list the directory and access its contents. If a user only has read access when a directory, the names of the files in it can be listed. But no other information including permissions or timestamps are available, nor can they be accessed. If a user only has execute access when Edenic tree, he can't list the names of the files in that directory. But if he already know the name of a file which he has permission to read, then he can access the contents of that file by explicitly specifying the file name. A file may be removed by anyone who has write permission to that directory. In which the fiery sides, regardless of the ownership or permissions on the file itself. But this can be overridden with special permission, like the sticky bit permission, which we will discuss later. Viewing file and directory permissions and ownership. The dish long listing option of the ls command will expand the file listing to include both the permissions of a file and the ownership, User and Group. While the command ls dash l directory name will show the expanded listing of all of the files that reside inside the directory. In this example, I added the DSD option to the ls command to prevent the descent into the directory and see the extra bended listing of the directory itself. Note that linux permissions only applied to the directory or file that they are sit on. And permissions on a directory are not inherited automatically by the subdirectories and files within it. However, permissions on a directory may effectively block access to its contents. All permissions in Linux are sit directly on each file or the directory. The read permission on a directory, and Linux is roughly equivalent to list folder contents in Windows. And the write permission on a directory in Linux is equivalent to modify in Windows, it implies the ability to delete files and subdirectories. In Linux, a fright and the sticky bit are both sit on a directory, then only the user that owns a file or subdirectory in the directory may delete at which is close to the behavior of the windows, right? Permission route has the equivalent of the windows full control permission on all files in Linux. However, the root may still have access restricted with the system security enhancing Linux policy and the security context of the verses and files in question. Security enhancing Linux is a security architecture for Linux systems that allows administrators to have more control over who can access the system. It was originally developed by the United States National Security Agency as a series of patches to the Linux kernel using Linux security modules. And those release to the open source community in year 2 thousand and those integrated into the upstream Linux kernel in year 2003. Security enhancing Linux defines access controls for the applications, processes, and files on a system. It uses security policies, which are a set of rules that tilt security enhancing Linux, what can or can't be accessed to enforce the axis by a policy. Let's take some examples. Here. I used the id command to get the groups for each user. Then I read the erected the results to the user's underscore groups file. As you can see here. The user MOOC groups are mu and test. And the user Tom groups are Tom and test. The user Judy groups, Judy and Yaro. And the user Sarah groups, our sorrow and Yaro. And here the ownership of the new dire directory. Tom and test, the user stone. And the group is test. And the ownership or these four files, mov file one, the user mu and the group move. More 5-2 User and Group test. Tom file one user Tom and group test. And don't fight to user Tom and group test. According to what you are seeing here, is the only person who can change the contents of file one as he has right permissions on the file, new file one is the owner and no one else is listed as a member of the group MOOC. And their permissions for other don't include write permission. Tom can view the contents of mov file as a member of the group test. And that group has read only permission or new file too. Even though either has right permissions, group permissions take residence. Tom can't delete New File. And New File too. Tom has right permissions on their directory containing both files. So he can read any file in that directory. Judy, can it change the contents of mov file to since Judy is not mu and it is not a member of that, is to group either permissions obliged to hear, and those include write permission, MOOC and to change the contents of DOM file one is more is a member of the group. And that group has both read and write permissions on DOM file one. Dome can view and modify the contents of Tom phi as he owns the file, and hence both read and write access to Tom file too. More can view but not modify the contents of Tom 5-2 as he is a member of the test group. And that group has read only access to 2m Phi to Judy and Sarah don't have any access to the contents of don't file to as other permissions obliged to Judy and Sarah. And those permissions don't include read or write permission. I hope this has been informative for you and I'd like to thank you for viewing. 40. 02 Managing File System Permissions from the CLI: Managing file system permissions from the command line. After completing this lecture, you should be able to change the permissions and ownership of files using command line tools. Changing file and directory permissions. The command used to change permissions from the command line is the chmod command sort for change mood has permissions are also called the mood of a file. The chmod command takes ML machine instruction, followed by a list of files or directories to change. The permission instruction can be issued either symbolically using the symbolic method or numerically using the numeric method. First, the symbolic method keywords. The chmod command syntax can be written as chmod, followed by who, what end, which followed by file name or directory name. Here, instead of who, the symbolic method keywords will be U for user, G for group, o for other, and E for all. And instead of what, we can use, the plus sign for, the minus sign for Remove and the equal sign to set exactly. And instead of which, we will use the R character for lead, the W character for right, and the x character for execute. The symbolic method of changing file permissions uses letters to represent the different groups of permissions. For the user, G for group or for other, and E for all. With the symbolic method, it is not necessary to set a completely new group of permissions. And still it is possible to change one or more of the existing permissions. To do this, you can use three symbols, the plus sign to add permissions to asset. The minus sign to remove permissions from a set. And the equal sign to replace the entire set for a group of permissions that are permissions themselves are represented by a single letter, r for read, w for write, and X4 execute. Second, the numeric method. The numeric method syntax is represented as chmod, followed by three hashes representing three octal numbers, which represents user, group and other, followed by filename or directory name. In the numeric method, each digit represents an access level. User, group and other. Each hash represents the sum of permissions granted read, write, and execute for each access level, with his will equal seven. A full permission is granted. Read, write, and execute, as it will be the sum of 4424, right? And one will execute. Using a numeric method. Permissions are represented by a three digit number or four. When sitting advanced permissions, single octal digit can represent the numbers from 0 to seven. Exactly the number of possibilities for three bit number. To convert between the symbolic and the numerically presentation of permissions, we need to know how the mapping is done. In the three digit octane numerically presentation. Each digit standards for one group of permissions from left to right, User, Group and other. In each of these groups, start with 0. If the read permission is present, at four, a2 if the write permission is present. And one for execute. Luminary permissions are often used by advanced administrators since they are shorter to type and pronouns while still giving full control over all permissions. For any access level. If the full permissions are granted, read, write, and execute. We can represent it numerically using the octal number seven is, this number is the result of the addition of four plus two plus one. If a file permissions are shown like this, read, write, execute for the user. Read and execute for group. A noble mission for other. Note that the installation means that this is a file. And if it was a directory instead of the dish will be the D character. For the user. Read write execute is calculated numerically, is 44 plus 24, right? Plus one for x, qd equals seven. For the group. Read and execute is calculated numerically is for fluorine plus one for execute equal five. And for other users, no permissions is represented with 0. Voting these three together, the numeric representation of those permissions is 750. Note that this calculation can also be performed in the opposite direction. If we took the number 640 as an example, for the user permissions, six represents read and write. For, for read or write equals x, which displays is read and write. For the group. For only includes read ends please, as read only. And for other users, 0 provides no permissions. And the finite set of symbolic permissions for this file is for user readwrite, for group read only, and for other noble missions. Let's take some examples. To remove read and write permission for group and other compile one using the symbolic method. Now let's create another file, file to check permissions on files T2 to execute permission for everyone on using the symbolic method. To check. Now let's try changing permissions on a directory to create a new directory. Now to change permissions on this directory and to set, read, write, and execute permission for user heat and execute for group. A noble mission for other users using the numeric method. And to check. As you can see here, seven, granted read, write, execute for user. And five, granted read and execute for group. And 0. No permission for other users. Note that the 2D comments about the dish, our keys or option for recursively setting permissions when an entire directory tree, when using this option. Be sure to use the uppercase X permissions in instead of the lowercase x permission to indicate that execute permissions should only be set on directories and not regular files. For example, the following comment we recursively sit, read, and write access will assemble their directory and all its children for their group owner, but will only apply to execute permissions to directories, not regular files. To create new directory symbol there. To create three files inside this directory. To check and to check the Directory permissions. And they would create another directory inside symbol, that directory. To check recursively sit, read, and write access on assembled died directory and all the files and directories inside it for the group owner and applying execute permissions only on directories, regular files. You can enter the command. To check. Here, as you can see, all files in symbols dire directory have the read and write permissions for group, except the new directory has read, write, and execute permissions for group. Changing file and directory user or group ownership. And newly created file is owned by the user who can eat the file by default, the new file has group ownership, which is the primary group of the user creating the fight. Since Red Hat Enterprise Linux uses user private groups, this group is often a group with only that user as a member to grant access based on group membership, the owner or the group of a file, we need to be changed it file ownership can be changed with the change owner command. For example. To grant ownership of the file, file one to move, we can use the following command. And to check. The change owner command can also be used with an uppercase or option two recursively change the ownership of an entire directory tree. For example, to grant ownership of symbol direct directory, and all files and subdirectories within it. To move. You can use this command to check. And we can use the change owner command to change group. Would I save a file preceding the group name with a colon? For example, to change the group assembled there. To check. The change owner command can also be used to change both owner and the group at the same time by using the syntax owner column group. For example, to change the ownership of symbols dire to test and the group to TM, we can use the command to check nodes that only root can change the ownership of a file. Group ownership, however, can be set by root or the file's owner. The root can grant ownership to any group. While non-root users can grant ownership only two groups they belong to. Instead of using the change owner command, you can use the change group command to change the group ownership using the syntax. Change group, group name, filename. For example. To change the assembled dire group to test. To check that this command works exactly the same as changing ownership with the change owner command, including the use of the dash, uppercase, or option to affect entire directory trees. I hope this has been informative for you and I'd like to thank you for viewing. 41. 03 Managing Default Permissions and File Access: Managing default permissions and file access. After completing this lecture, you should be able to configure a directory, enrich newly created files are automatically writeable by members of the group which owns the directory. Also, using special permissions and default settings. Especially permissions. The set user ID or said Group ID permission on an executable file means that the command to run is the user or group of the file, not as the user that trend the comment. One example is the best would comment. The sticky bit for a directory sits especially restriction and the division of files. Only the owner of the file and route can delete files within a directory. An example is the TMP directory. Lastly, the set group ID permission on a directory means that files created in the directory will inherit the group affiliation from the directory, rather than inheriting it from the creating user. This is commonly used in group collaborative directories to automatically change a file from the default private group to the shared group. Effect is of special permissions on files and directories. Symbolically, the set user ID permission equal u plus S. The set group ID permission equal g plus s. And the sticky bit permission equal o plus t. And numerically, it would be the fourth preceding digit, the set user ID permission equal four. Said Group ID permission equal to. And the sticky bit permission equal one. When setting the set user ID permissions on a file, file executes as the user that owns the file, not the user that trend the file. And the wind sitting on a directory. There will be no effect. When setting the set group ID permissions on a file. The file executes as the group that owns the file. And on a directory, files newly created in the directory have the group owner set to match the group owner of the directory. And the wind setting the sticky bit permissions on a file, there will be no effect. And on Directory, users with the right permission on the directory can only remove files that they own. They can't remove or false seems to files on by other users. Settings, special permissions. Let's take some examples. To add the set group ID permission to that directory. To check. To set the set group ID permission and read write execute permissions for User and Group numerically and assembled dire directory. Here is the assembled diode directory is owned by user tests and group tests. To set new permissions on it. First, I need to change the route or use the sudo command to check default file permissions. The default permissions for files are said boy, the processes that create them. For example, thickest editors create files so the readable and writable but not executable by everyone. The same goes for shell redirection. Additionally, binary executables are committed executable by the compilers that can eat them. They make their command creates new directories with old permissions, sit, read, write, and execute. This means that before the mask is applied, a directory has permissions, treble seven or trivial, read, write, execute for user group and the other users. And they blame file has permissions. Trivial six or readwrite for user group and the other users. The you must value will be subtracted from this default permissions after the function has created the new file or directory. Thus, a directory will have permissions of 70-75 by default and file six 64 if the mask value is 002. Now to check the value for the user term. Now if we created a new file, test and check the file permissions. As you can see as the default permissions for oblique file is treble six. After subtracting the value of the US, it became 66 for meaning readwrite for User and Group, and Read Only for other users. Now to try and directories, to check. Here, as you can see, as the default permissions value for directories is triple seven. After subtracting the value, it became 70-75, meaning read, write, execute for user and the group. And read and execute only for other users. Every process on the system has a new mask, which is an octave Pete mask that is used to clean it. The permissions of new files and directories that are created by the process. If EBIT is set in the EU mask, then the corresponding permission is cleaved in new files. Instead of adding the symbolic values to each other as we change mood comment for calculating the permission on a new file, we need to be subtracted from the total possible access rights. In the previous examples, they, you mask value, cleaves the write bit for other users. The leading zeros indicate the special user and group permissions are not cleared. You must value of 077 with clear all the group and the other permissions of newly created files. You can use the human excrement with a single numeric argument to change the USC of the current shell. The numeric argument to be an octal value corresponding to the new value. If it is less than three digits, needing zeros are assumed. The system default you mask values for best shall users are defined in the sludge sludge profile phi n slash r c file. Users can override the system defaults in their base underscore profile file and don't base are S5. Let's take an example. If I set the value to 0, this setting will look mask any of the permissions of new files. I will create a new file and directory to check. As you can see, the file default permissions remains as it is. And the default directory permissions remains as it is triple seven. Now, if we set the value to 007, this setting will mask all of the other permissions of new files to check. And if we set the value to 0 to seven, this setting will mask right xs for group members and all of the other permissions of new files. To check. Now to change the default you mask for I'm privileged users to prohibit all Xs for users not in their group. First, you need to switch to the root user. Then you will need to modify the sludge stays best RC file and the sludge ETC, slash profile file. To change the default you mask for Bash shell users. You can use your choosing text editor like Nano or them. Since the default unesco ambivalent jet users is 0002. We look for the command in this piles that sets the mask to that value, and we will change them to set the 2007. Chris control x to exit. Enter to confirm the same name. I will create a new user to check the default value for new users. Do that other shells, such as TC shell, we have different system default initialization files in sludge, ETC. And user's home directory is. I hope this has been informative for you and I'd like to thank you for viewing. 42. 00 Section Seven Overview: Monitoring and managing Linux processes. The goal of the section to evaluate and control processes running on edit head Enterprise Linux system. After completing this section, you should be able to list and interpret basic information about processes running on the system. Control processes in the transition using best job control. To meet and controlled processes using signals. We need to resource usage and system load due to process activity. In this section, you will learn what a process is. The lifecycle of a process. Process states, listing processes, controlling drops, killing processes, monitoring process activity, using the system monitor too. 43. 01 Processes: Processes. After completing this lecture, you should be able to define what is a process and find what is a thread. And instance of a running program is called a process. Processes are also frequently referred to as tests. Every time you run a shell command, a program is run and fibrosis is created for a while. A computer program is a massive collection of instructions. Fibrosis is the actual execution of those instructions. Several processes may be associated with the same program. In Linux. And abstraction of process is however, incomplete without discussing threads. Sometimes called lightweight processes. By definition, method is an execution context or flow of execution in a process. Thus, every process consists of at least one thread. Fibrosis containing several execution threads is said to be a multithreaded process. Each thread has its own ID, program counter, process, tech, and a set of registers. Each process consists of system resources that are allocated to it and addresses piece of allocated memory, operating system descriptors of resources that are allocated to the process, security attributes and the process state. The environment of a process includes local and global variables, a current scheduling context, and allocated system resources, such as file descriptors and network ports. Thanks for viewing. 44. 02 The Life-Cycle of a Process: The life cycle of a process. After completing this lecture, you should be able to define the lifecycle of a process. A new process referred to as the child is normally created when an existing process, referred to as parent makes an exact copy of itself in memory using the fork function. The child process will have the same environment as its parent, but only the verses ID number is different. Every new process is assigned a unique process ID for tracking and security. The process ID and the Barons process ID are elements of the new process environment. Burned processes are processes that create other processes during runtime. And the child processes are processes created by other processes during runtime. Any process making it a child process. And all processes are descendants of the first system process, which is system D on Elhadad Enterprise Linux system. The system d process is the mother or parent of all processes on the system. It is the first program that is executed when the Linux system boots. It manages all other processes on the system. It is started by the kernel itself. So in principle, it doesn't have a parent process. The system d process always has process ID of one. It functions as an adoptive parent for all orphaned processes. The fork and exec functions through the fork routine. A child process inherits security identities, previous and current file descriptors, and the resource privileges, environment variables. And the program could a child process within exec, its own program could normally aberrant process sleeps while the child process runs, setting a request width to be signaled when the child completes. Upon exit. The child process has already closed or discarded its resources and environment. That remainder is referred to as a zombie. The bird signaled awake when the child exited, cleans the remaining structure, then continues with its own Brooklyn could execution. 45. 03 Process States: Process states. After completing this lecture, you should be able to define process states. In a multi-tasking operating system. Each CPU or simi, you can be working on one process at a single point in time. As a process runs, its immediate requirements for CPU time and the resource allocation change. Processes are assigned a steep which changes as circumstances require processes, states defined what process is doing and what is expected to do in near time. Performance of the system depends on a major number of process states. From the birth till death. Process has a lifecycle going through several states. Rodney process states are running or runnable. Sleeping or waiting. Stopped. Zombie. Let's dive into each state. Process state running. Kendall defined state name, running. This is the most healthy state of all. It indicates a process is active and serving its request. Process is probably getting system resources, especially CPU, to perform its operations. Running process is a process which is being served by CPU. Currently, It can be identified by state flag are in BS or top command's output. As you will see later in this section, enlisting processes. The runnable state is when a process has got all the system resources to perform its operation except CPU. This means process is ready to go once CPU is free. Runnable, processes are also flagged with the state flag or the process state sleeping. The sleeping process is the one who waits for resources to run. Since its own weightings ten gives up CPU and goes to sleep mood. Once it's required resource is free, it gets placed in scheduler cue for CPU to execute. There are three types of sleep moods. Uninterruptible, uninterruptible, and capable. Uninterruptible sleep mood. The Kernel defined state name, desk interrupt will. In this MOOC, the process is waiting for some condition as how do we request system resource access or signal? When an event or signals satisfies the condition the process returns to running. These processes are shown with the state S, MBS or top comments output. Uninterruptible sleep mood. Can then define state name, desk, uninterruptible process in this sleep mode gets its timeout value before going to sleep. Once the time outset of eta weeks, re-tweets when weighted upon resources become available for it. It can be identified by state D and outputs. The kilovolt sleep mood. Kendall defined state name. That's scalable. This sleep mood is identical to the uninterruptible the state, but modified to allow the reading task to respond to a signal to be killed. This process plague is K, but utilities frequently display capable processes as this tape. The process state stopped. The process is stopped, has two candles defined states and both have the same T flake. First, desk top. And second, task three is in Kendall defined state desk stopped. The process has been stopped, usually by being signaled by a user or another process. The process can be continued by another signal to return to running. And in Canada, undefined state desk is a process that is being debugged, is also temporarily stopped and shares the same T state flag. The processes state zombie. Zombie has two Kernel defined states. Exit zombie with Z state flag and exit date. With excess state flag. In the kernel defined state exit zombie. A child the process signals experience as it exits. All resources except for the process identity are released. It can be identified by state x0 in outputs and in covalent defined state exit. After the Barents receives the exit signal from the child process, the parent cleans up the remaining child process structure and removes the processes slot in the table. The process is now released completely. This state will never be observed in process listing utilities. Note that process can stay in zombie mood if its parent died before it releases giant processes slot in the table. It can be identified with z and outputs. The complete life cycle of process can be circled. It's been waiting, runnable, running, stopped, zombie, and last removed from process table. Thanks for viewing. 46. 04 Listing Processes: Listing processes. After completing this lecture, you should be able to view and interpret process listings and use the BS comment. Viewing active processes in Linux. There are several Linux tools for viewing and listening running processes on the system. The two traditional and well-known RBS and top Kamen's Rose's status command is used for listing processes. The command can provide detailed process information. It needs the process information on the virtual files in the file system. The BS command is one of the important utilities for system administration, specifically under process monitoring, to help you understand what is going on, dynamic system provides numerous options for manipulating the output according to your needs. Let's try using ps command here to processes only our showed the best shell. And ds, which itself is a process which dice as soon as it is displayed. By default. Bs with no options, selects all processes with the same effective user ID as the current user and associated with the same terminal where BS was invoked. Note that the Linux version of VS sub bolts three options permits, including Unix options, which may be grouped and must be preceded by a dash. Bsd options, which may be grouped and must be used with a dish. And new loan options which are preceded by two digits. For example, the result of using the Dutch auction for Unix is not the same when using the option for BSD. Using the AUX option with the ps command. Adding the AUX option to the ps command, we provide a full listing of the current processes. The option tells me to list the processes of all users on the system rather than just those of the current user. The u option tells VSS to provide detailed information about each process. And the option adds to the processes that have no controlling terminal, such as demon that are started during booting. As the number of processes can be quite long and LQ by more than a single screen. Here i biped output of that to the less common, which lets it be viewed one screen at a time. The output can be advanced one screen port by pressing the space bar. And moved one screen backward by pressing the geeky. Among the information that provides about each process is the effective user name of the Process Owner, user. The process ID, the percentage of CPU used by the process, the percentage of memory used by the process. The virtual memory size in kilobytes, the land is swept physical memory size in kilobytes. The location of process standard known as the controlling terminal. The processes state could the starting time of the process, the length of time the process has been active, and the command that initiated the process. Now let's check the meaning of the different values that are shown in the state column IV to exit. You can rescue at any time. We can use the manual helped to check the values of the state column values. Here are different values that lasted column will display to describe the state of a process. As an example, d will be used for an interrupt sleep. And I put idle kernel threads are for running or runnable. And for the b is d formats, the state keyword is used. Additional characters may be displayed. For example, uppercase N, for low-priority, and lowercase S, four session leader. Using the option with the BS. Along listing options, LAX provides more technical detail. As you can see here, each process has a flag represented by uppercase character. Take numbers from one to five. We can check the meaning also by using the man command. As you can see here, one will mean poor kid but didn't exist. And for superuser privileges. And if the number five appears to you, it will mean that both legs apply. 14. And if 0 is shown, it will means that neither plague applies. Also another new columnists appearing here, which is Wusheng column. And it is used to show memory address of the event the process is waiting for. Using the option with the comment. And alternative set of options for viewing all the processes running on a system is that this option? The option, generates a list of information about every process currently running. And the dish if option generates a listing that contains fewer items of information for each process, then the option among the columns displayed by VS DCF command is the user ID column. The user ID column contains the username of that count that owns the process, which is usually the same user that started the process. And the time column is used to display the time to process started or the starting did 50 started more than 24 hours ago? Processes in brackets usually appearing at the top are scheduled kernel threads. Using the BS3 command. The command can display in tree format to view parent-child relationships using the VST command. As you can see here. The first process is started in the system, and which is the parent of all processes is system d. The addition of the dish B option to the BS3 comment. We also show the processes ID. For example, it should heat the system d process with grosses ID1 and network manager with bruises ID one hundred one hundred and fifty five. The processes that are directly connected to the main stem, which is the vertical line extending consistent d, along the left-hand edge of the screen are listed by default in alphabetical order. This is contrast to BS, which by default list the processes in the order in which they were created. The BS common default output is unsorted. Order matches that of the system process table, which reuses table rows as processes die and new ones are created. For example, to sort the BS DCF comment output, you can use the command node that BS displays once. You can use the top Common Core update process, display is a powerful system monitoring tool that offers you a dynamic real time view of a running system as shown. By default, the dope command output is refreshed every three seconds. Later, I will talk about it in details in this section. I hope this has been informative for you and I'd like to thank you for viewing. 47. 05 Controlling Jobs: Controlling jobs. After completing this lecture, you should be able to explain the terms foreground, background and controlling terminal. Using drop control to manage multiple command line. Slope control is a cadential feature, allowing a single shell instance to run and manage multiple commands. Without job control. Apparent shell forks a child process to run a command, sleeping until the child process exits. As in this example. With the Shell prompt read displays, the parent-child has returned. With job control. Commands can be selectively suspended, resumed, and run a synchronously allowing the shell to return for additional commands. Wild child processes run. Foreground process is a comment running in a terminal window. The terminals device ID. The processes controlling terminal. Foreground processes receive keyboard generated input and signals and are allowed to read or write to the terminal via standard input and standard output. Process session is created when a terminal or console first ovens at login or by invoking a new terminal instance. All processes initiated from a terminal shaded the same session ID. Within a session. Only one process can be in the foreground at a time. A back ground process is started without a controlling terminal because it has no need for terminal interaction. In a p s listing background processes such as service demons and kernel threads, split a question mark in the TTY column. Background processes which improperly attempted to read from right to the terminal may be suspended. Running jobs in the background. Any command can be started in the background by appending an ampersand to the command line. For example. The best shelf displays a job number unique to the session and the process ID of the new child process. As you see here, the cadential doesn't wait for the child process and reads, plays the shell prompt. The best conventional tracks job's recession in a table displayed with the job's command. Background, jobs can reconnect to the controlling terminal by being brought to the foreground using the FG command with the job ID. As in this example, the sleep command is now running on the controlling terminal. And the convention is again, asleep, waiting for this child process to exit, to recede to the background or to send any comments in which the drilling ampersand wasn't originally included. Since the keyboard generated suspend Request Control Z to the process. This has been, takes effect immediately. The job is pleased in the background, bending output and keyboard type ahead or discarded. Using the bs option GI. Please, job information including the initial command shell of each session. Since the sleep example command is currently suspended, the steed flex blade is uppercase T. To restart the process in the background using the bg command with the same job ID. If the user attempts to exit a terminal window with suspended jobs, the suspended jobs are killed. Thanks for viewing. 48. 06 Killing Processes: Killing processes. After completing this lecture, you should be able to use commands to Cal and communicate with processes. Define the characteristics of a daemon process. And in the user sessions and the processes. Roses control using signals. Signal is a software interrupt delivered to a process. It report event to an executing program. Events that generated a signal can be an error external or by explicit requests. This table lists the fundamental signals used by system administrators for routine process management. For example, sick kill immediately terminates a process and the process will not be reformed any clean up operations. It can't be ignored or handled. And take their causes Brooklyn termination. It can be ignored or handled, and it allows self cleanup. Each signal has a default action, usually one of the following. Stop and count. For example, as you can see here, sick gill action is term and term default action is to terminate the process. Note that the signals sickle and things can't be cold blooded or ignore. Although sector is the default signal, cycle is a commonly misused administrator favorite. Since the signal can be handled or ignored, it is always fatal. However, it forces termination without allowing the process to run self cleanup routines. It is recommended to send sector first, then Detroit with sickle only if a process fields to respond. Signal numbers vary on different Linux hardware bled forms, but signal nims and meanings are standardized. For command, use. This advice to use thickness names instead of numbers. The numbers discussed in this lecture are for intellects 86 systems. Programs can be pre-built for expected events signals by implementing handler routines to ignore Ripley's or extend a signals default action. For a complete list and description of signals, you can consult the manual for signaled by running the command, man, seven signal. Commands for sending signals by explicit requests. Users signal their current foreground process by typing a keyboard control sequence. Control Z to suspend, Control-C to kill, and Control backslash to cool down by a process. Note that to signal a background process or processes in a different session requires a signal sending command. Signals can be specified either by name or by number. Users may kill their own processes, but root privilege is required to kill processes awed by others. The kill command sends a signal to a process by ID, despite its name using the syntax kill B ID. It can be used for sending any signal, not just those for the meeting broke grams by specifying the signal number after the kill command. That if no signal is specified, the term signal 15 is sent. For example. And to check. Or you can provide the signal number using the command. To check. You can run the command with the l option to see signals on the system with the corresponding numbers. Old foo, you can use the kill command to send a signal to one or more processes matching selection criteria, such as a command name, processes owned by a specific user or system wide processes. Let's take some examples. Now to kill this leap command, using the kill command. To check. Another example. Do you use the kill command to get multiple commands at the same time? To check. The p command, like kill, all, can signal multiple processes. It uses advanced selection criteria, which can include a combination of command, user ID, Group ID, parent process ID, end terminus. You can check the vehicle command options using the dash dash help lagging users out administratively. The w command views users currently logged into the system and their cumulative activities. You can use the TTY and from columns to determine the user's location. All users have a controlling terminal listed as BTS. While working in a graphical environment window or d2y in when a system console, alternate console or other directly connected terminal device. You can discover how long a user has been on the system by viewing decision lagging time. For each session, CPU resources consumed by current jobs included background tasks and the children are in the JCB EU column. Current foreground process CPU consumption is in the VCB you column. Users may be forces of a system for security violations, resource over allocation, or other administrative needs. As a user, you are expected to quit unnecessary applications, close and use common shells and exit lagging sessions. We requested when situations occur in which users can't be contacted or head unresponsive sessions. Runaway resource consumption, or improper system access. Decisions may need to be administratively terminated using signals. Let's create some processes for the user test. Now switch to the root user. Processes and sessions can be individually or collectively signaled. To terminate all processes for one user. You can use the command because the initial process in elegant shell is designed to handle session termination requests and ignore unintended keyboard signals, killing all of our users or processes and lagging shells requires using the signal. First to list all the processes on by the user test, we can use the grep command. The peak grip comment sessions for processes currently running on the system based on a complete or partial process name, username, where other specified attributes. Here, I used the dash l option to list the process ID and the process name and the desu option to match by effective ID. To kill all the processes on by the user test. You can use this command to check. As you can see, because the session leader here, which is the best login shell, is designed to handle session termination requests. It successfully handled and survived determination requests. But all other session processes are terminated. To kill all of our users processes including login shell. This requires using the same scale signal. When processes requiring attention are in the same login session, it may not be necessary to kill all of our users processes. Let's open a new tab. Switch to the test user. You can determine the controlling terminal for decision using the TTY command. Switch to the first step. And the test user terminal. You can use the command. The same selective process definition can be applied using parent and the child process relationships. Use the BS3 DISP command to view a process tree for the system or a single user, then you can use the parent process ID to kill all the children they have created. Let's try. A new tab. Can lead to new processes. Then go to the root tip. Use the BS3 DISP command to get the processes with their IDs. Now to kill these processes using the process ID, this command, uppercase P option, only tried the processes of the given parent to check. And if we use the thick girl to check, this time, the barren space login chilled survives because the signal is directed only at it's the child, the processes. Thanks for viewing. 49. 07 Monitoring Process Activity: Monitoring process activity. After completing this lecture, you should be able to interpret uptime, system load and load averages, monitor real-time processes. Let's understand two important prisoners in a Linux system. System load and load average. On Linux. The system load is a measurement of the computational war the system is performing. This measurement is displayed as a number. A completely idle computer has allowed average of 0. Each running process, either using or waiting for CPU resources, S1 to the load average. So if your system has a lot of, for the four processes are either using or waiting for the CPU. Unix systems traditionally just counted processes waiting for the CPU. But Linux also counts processes waiting for other resources. For example, processes waiting to read from right to the desk. A computer might have a lot of 01 split second and a lot of for the next split second as several processes use the CPU load average. The load average is useful to understand how your system is performing. If it is overloaded, you may need to deal with a process that is wasting resources, provide more hardware resources, are moved some of the work load to another system. On multi-processor system, the load is relative to the number of processors cores available. The 100% utilization mark is one on a single core system to when a dual core system. And for unequipped core system. Same with CPUs. A load of one is 100% CPU utilization on single core books, and the load of two is 100% CPU utilization on a dual core box. The load average is shown in many different graphical and terminal utilities, including in the top comment. The graphical groom system monitoring tool. And the easiest and the most standardized way to see your load average is to run the uptime command in a terminal. This command shows your computer's load average as well as how long it has been powered. On. Understanding the load average output. The first time you see a load average, the numbers look fairly meaningless. It is an example, load average. From left to right. These numbers show you the average load over the last one minute, the last five minutes, and the last 15 minutes. In other words, the above output means the load average over the last one minute is 1.00. Two. The load average over the last five minutes is 0.70, and the load average over the last 15 minutes is 3.09. The time periods are omitted to save space. Once you are familiar with the time periods, you can quickly glance at the load average numbers and understand what they mean. Let's use the above numbers to understand what the load average actually means. Assuming you are using a single CPU system. The numbers tell us that over the last one minute, the computer was overloaded by 2% on average. And bone 0-2 processes, we're waiting for the CPU. Over the last five minutes, the CPU idle for 30% of the time. And over the last 15 minutes, the computer was overloaded by 209% on average. And 2.0. nine processes were waiting for the CPU. You probably have a system with multiple CPUs or a multi-core CPU. The load average numbers or Cabot differently on such a system. For example, if you have a load average of two, when a single CPU system, this means your system was overloaded by 100% the entire period of time. One process was using the CPU, while one other process was waiting. And a system with two CPUs, this would be complete usage. Two different processes will using two different CPUs the entire time. And on a system with four CPUs, this would be half of usage. Two processes, we're using two CPUs. Wife two CPUs will sitting idle. Node that. To understand the load average number, you need to know how many CPUs your system has allowed. Average of five would indicate a system with a single CPU was massively overloaded, but it would be fine on a computer with its CPUs. Displayed load averages represent all CPUs. Linux counts, each physical CPU, core and microprocessor high birthrate as separate execution units logically represented and referred to as individual CPUs. Each CPU has independent request queues. You can view the sledge broke slash CPU info file for the kernel representation of system CPUs. With more than one CPU, several programs can be executed simultaneously. To find the number of processing units available on a system, we may use the n block or LS CPU commands as follow. Another way to find the number of processing units using Grip command is, for performance purposes, a machine with a single dual-core processor, basically equivalent to a machine with two processors with one core Each. This means that to quit course is equal to four dual course, which is equal to its single cools. All of them are it cuz if you divided the displayed load average values by the number of logical CPUs in the system. And value below one will indicate satisfactory resource utilization and minimal width times. And a value above one will indicate resource saturation and some amount of service waiting times. Thanks for viewing. 50. 08 Real time Process Monitoring: Real time process monitoring. The top comment. Took is a powerful system monitoring tool that offers you a dynamic real-time view of a running system as shown, displaying a summary header followed by abrasive or Threadless. Similar to BS information. Unlike the static ps, output, dope continuously refreshes at a configurable interval and provides capabilities for column reordering, sorting, and highlighting. By default, the top command output is replaced every three seconds. In order to change this interval. Head the D key while the top command is running. You can then enter the new time in seconds. And breast enter. User configurations can be saved and meet resistance. The tasks through above list is total count of all the states in its output header. For each listed process, the top command displays the process ID, the effective user name of the process owner. The barriers, the lice value, the amount of virtual memory the process uses. The amount of nano swept the physical memory, the amount of shared memory. The Bruce's status field, the percentage of CPU usage, the percentage of memory usage, the accumulated CPU time, and the name of the executable file. The fundamental keystrokes in top. You can press H to C Help options. And then you can rescue or skip to return to the top display. Raise em to sort by memory usage in instead of CPU. You can press the number one to toggle showing CPU usage of all your CPU. If you have more than one CPU on your system. Rescue and enter a username to display processes only for a particular user. Pressing Enter or Space keys immediately refreshes the display. And you can press Q at any time to quit. A common practice is to use dope to find processes that are consuming too much memory or processing power, and then act on those processes in some way. A process consuming too much CPU can be really nice to give at least priority to the processors. And the Bras is consuming too much memory can be killed. With doped running. Here is how to recognize or kill a process. Renouncing a process. First, note the process ID of the process you want to revise and breasts are with the process ID to renounce message appears. Type of a process ID of the process you want to realize. And when prompted to recognize the process ID to a value, type in a number from negative 19 to 20. The priority or importance of a job is defined by its nice number. I broke em with a high nice number, is friendly to other programs, other users in the system. And it is not an important job. The lower the nice number, the more important a job is, and the more resources it will take without changing them. Making a jump nicer by increasing its nice number is only useful for processes that use a lot of CPU time, such as compilers, myth, obligations, and the like. Processes that always used a lot of input-output time are automatically rewarded by the system and given a higher priority, which means a lower nice number. For example, keyboard input always gets the highest priority on a system. The default nice value of all the processes is 0. Killing a process. The process ID of the process you want to kill. And the best. You can type 15 to terminate clearly using s6 term signal or nine to just kill the process outright using the SEC kill signal. Thanks for viewing. 51. 09 The System Monitor Tool: Using the num system monitor tool. After completing this lecture, you should be able to use the system monitor tools. The processes tip of the system monitor tool allows you to view, search for, change the validity of and processes from the graphical user interface. To install the tool. Issue this command as root. To start the system monitor tool, select applications. System monitor, or prompted type. Grew this system. This monitor. Click the processing step to view the list of running processes. For each listed process, the system monitor tool displays its current status, percentage of the CPU usage. The nice value, the process ID, memory usage, the channel the process is waiting in. And additional details about the session. To sort the information by a specific column in ascending order. Click the name of that column. You can click the name of the column again to toggle the sort between ascending and descending order. By default, the system monitor tool displays a list of processes that are owned by the current user. Selecting various options from the view menu allows you to view only active processes. View all processes. View your processes. View process dependencies. Refresh the list of processes. View a memory map of selected process. View the files opened by a selected process, and additionally, various options in the Edit menu allows you to stub process, continue running a stopped process into a process, kill a process. Change the priority of a selected process, and edit the system. Monitor preferences, such as the refresh interval for the list of processes, or what information to show. You can show any process properties by selecting it and click the Show Process Properties button. You can also end up process by selecting it from the list and clicking the End Process button. And if the process is owned by other user, you will first need to open the system when you took tool as a root user. Thanks for viewing. 52. 00 Section Eight Overview: Controlling surfaces and demons. The goal of this section is to control and monitor network services and sustainably ones using system d. After completing this section, you should be able to describe the role of system D in a Linux system. Let's test them demands and network services started by system d and socket unit control system demons and network services using system CTL. In this section you will learn system d rho explanation, important features offered by system, the limbic system initialization, identifying automatically started system processes, system tools, system CTL and system d units, service states, system the unit status, listing unit files with system CTL, controlling system services, starting and stopping system demons. You need dependencies. Masking services, enabling system demons to start or stop at boots. System CTL commands. 53. 01 Systemd: System d. After completing this lecture, you should be able to explain what system d is and the role of system d process in a Linux system. System d is a system and service management demon. It provides a method for activating system resources, server demons, and other processes, both at boot time and on a running system. Its mean IM is to unify Service Configuration and behavior across Linux distributions. The name system D adheres to the unix convention of naming demons by appending the letter D. It also please on the term system d, which refers to a person's ability to adapt quickly and improvise to solve problems. Since 2015, the majority of Linux distributions have adopted system D, having replaced other systems such as the Unix system v and b is d. Init systems. Read head is the inventor and the primary booster of system d. So the best districts for bleeding with it already had Enterprise Linux clones like Santos and scientific Linux. Similar to any system d is the parent of all other processes directly or indirectly, and is the first process that starts at boot, hence, typically assigned a process ID one. System D may refer to all the packages, utilities, and libraries around the moon. It was designed to overcome the shortcomings of init. System d itself is a background process which is designed to start processes in parallel, thus reducing the boot time and computational overhead. The main reason that there was a need to replace in it is that in process started serially, meaning that one task starts only after the last task Startup was successful and it was loaded into memory. This often resulted into delayed and lung booting time. However, system D was not designed for speed, but for getting the things done neatly, which in turns, avoid all the unnecessary delays. Demons are processes that we've run in the background performing various tasks. Generally, demons start automatically at boot time and continue to run until shut down or until they are manually stopped. To listen for connections. A daimon uses a socket, which is the primary communication channel with local or remote clients. Sockets may be created by demons or maybe separate it from the demon and be created by another process, such as system d. The circuit is best to the demon when a connection is established by the client. A service often refers to one or more demons, but starting or stopping a service may mislead, make a onetime change to the state of the system, which doesn't involve leaving a daemon process running. After all. A few of the new features provided by system d include Keene State forward and efficient design. Similar put process, concurrent and parallel processing output, symbol unit syntax, ability to remove optional components, low memory footprints. In proof technique to express dependencies. Initialization instruction written in config file and not in shell script, make use of unix domain sockets, job scheduling using system D, calendar timers, event logging with journal D, choice of logging system events with system D, as well as this log. Logs are stored in binary file system, the state can be preserved to be called later in future. Users login managed by system D, slugging D. Better integration with gloom for interoperability. And everything is at one, please. At the end of the boot process, the Linux kernel load system d and bases control over to it, and the startup process begins. During this step, the candle initializes the first userspace process, system d with process ID one, and then goes idle and lists called again. System D prepares the user space and brings the Linux host into an operational steep by starting all other processes on the system. Simplified overview of the entire Linux port and startup process. First, the system parse up, then buys, does minimal hardware initialization and hands over control to the bootloader. The bootloader calls the kernel. Then the kernel loads and initial RAM disk that loads it, the system drives and then looks for the root file system. Once the candle is set up, it begins the system de-initialization system. Then system detects over and continues to mount the hostess file systems and storage services. Thanks for viewing. 54. 02 Identifying Automatically Started System Processes: Identifying automatically started system processes. After completing this lecture, you should be able to list system demons and network services started by the system disservice and socket units. System d units, iron. It is assisting the object that performance or controls a particular task or action. System B uses units to start, stop, managed, service, organize boot process, maintain tasks and the processes create sockets, mounted file system, and initialize hardware system. The unit consists of an EM type and configuration pile. The name provides a unique identity to the unit. The type helps they only to group with other similar types of units. And the configuration file defines the responsibility or test of the ionic. System D tools, system dynamics, common system administration tasks, easier to manage with its system CTL and journal CTL commands. The system CTL command can be used to gather detailed information about the overall state of your server and any individual unit type. It can stop and start the server and modify the system state or the system. These journal city L2 provides a centralized process and system blogging tool. This command allows you to query the system D journal, which creates and maintains in Brexit journals from logging information that is pulled from different areas within the system. Areas like standard output and standard error of service units, like messages, BSE, slug, and Canon log messages. In this way, system administrators can use a single tool to monitor and debug observer system CTL and system d units. The system CTL command is used to manage different types of system, the objects called units. To list all available unit types, you can use the system CTL, DST, help command. Service states. The status of a service can be viewed with system CTL, status, main.out type command. If they only type is not provided. System city L will through the streets of service unit if one exists. System the unit status. Several keywords indicating the state of the service can be found in the status output. For example, the loaded status means that valence configuration pile has been successfully read and processed and the active states means successfully executed. Let's take some examples. Checking system diversion. To fool the version number of system D and your Linux system, you can use the command view units. System B uses units which can be Services, mountable. Devices also cuts. You can use the system CTL command to manage all these types of units. By default. When you run the system CTL command without any arguments, it will display a list of all loaded system d units, including services showing VM status with our active running, extend or failed, and the description using the list, this unit sub command will show the same result that the system CTL command would automatically the output with less view all available unit piles on your system and we'll stick. You can use the command. Here. As you can see in the output ion, it can be in three states. Enable, disable, and static. If I own it is in the enabled state, the system distorts it at boot time. If it is in the disabled state, the system D doesn't start it at startup. And if I unit is in the static state, neither the system restarts it at startup, nor allows us to change its state. In other words, if Ionic is in the disabled or enabled steep, you can change its state using the system CTL enable or disable command. But if Ionic is invest static steep, you can't change its state. Technically. If ion it is in the static state. This means that the only doesn't have the installed section in its configuration file, which is required to start a unit at boot time. The difference between the system CTL or system CTL list this unit's commands and the system CTL list this unit based fights command, is that the first two commands give a runtime snapshot of units. While the third command displays the status of units at startup. To list all field units, you can use the command. And filter the output to view only filled services. You can use the command to list all available units in a particular type. You can use. For example, the following command list is all available units in the type service. Option instructs the system CTL command to include inactive units in the output. Also, you can use the type option to filter the output by type. For example. Or in the output, the first column lists the name of the second column displays with configuration was loaded blueberry or not. The third, fourth columns. And the last column provides a description of day on it. You can filter the output to new, more specific list of units. For example, to view the list of only active units in the type service, you can use the command to filter the output of available unit piles based on type. And instead, you can use the following command. All loaded but active services running and those that had the option with a value of active, for example. And to get a quick glance of all loaded and activity running services, you can run the command. Thanks for viewing. 55. 03 Controlling Services and Daemons: Controlling system services. After completing this lecture, you should be able to control system demons and network services and view the status using system CTL surfaces status. You can use the status option with the system CTL command. System CTL list based unit despite command to show the state of a unit. For example, to show the network manager service status, you can use the command. Another example to view the status of only the types. Ok, we can use the command. Alternate commands can also easily showed the active and the enabled state. For example, to determine if the service is active without displaying all of the status information, you can use the command. And to determine if the service is unable to start at the system boots, you can use the command starting, stopping, restarting and reloading system demons on a running system. The system CTL command allows you to start, stop, or start a service. Also, you can tell a service to reload it's configuration before starting node that changes to configuration file or other updates to a service may require that the service be restarted. Service that is no longer used may be stopped before removing the software. That is not frequently used, maybe manually started by n administrator only when it is needed. If the user is the route, you need the root privileges to manage the unit. Let's take some examples on managing services on a running system using the SSH ED service. First, let's view the status of the SS HD service viewpoint that a process is running. Just stop the service status. To start the service and view the status has changed. To stop the service in a single command. Ooh, instructions for a service without top versus ID will not change. Unit dependencies. Services maybe started as dependencies of other services. If a socket unit is enabled and the service unit with the same name is not, the service will automatically be started when a request is made on their network. Socket. Services may also be triggered by Beth units when our file system condition is met. For example, a file list into the brand spool directory will cause the caps print service to be started if it is not running. To completely stop renting services on a system, you need to stop filling units, service, and socket. Disabling the service will disable the dependencies. You can use the system CTL lists these dependencies unit command to print out a tree of what other units must be started if the specified during, started. Depending on the exact dependency, the other unit may need to be running before or after the specified when it starts. Adding the desk distributors option to this command will do what you need to have a satisfied unit started in order to run. For example, masking services. At times, a system may have conflicting surfaces installed. For example, there are multiple methods to manage networks and firewalls to prevent an administrator from accidentally starting at service. That service may be masking. Masking will create a link in that configuration directories so that if the service is started, nothing will happen. In other words, you can mask a service or other unit to prevent it from starting up at all. You would need to unmask it before it can store it in the future. For example, to mask the network manager service, you can use the command. To check the network manager service. Use the command. Note that a mascot service cannot be started manually or automatically. Enabling and disabling system demons to start or stop at. Starting a service on a running system doesn't guarantee that the service will be started when the system reboots. Similarly, stabbing a service when arraying system will not keep it from starting again with the system reboots. Services are started at boot time when links are created in the appropriate system D configuration directories. These links are created and removed with system CTL commands. In other words, you can use the system CTL enable command to have system view automatically stored a service or other type of unit at boot up. And you can use the system CTL disable command to disable a service and stops it from starting automatically with your computer. Let's take some examples to view the status of a service. For example, the SSH servers use the command. The status disabling a service doesn't stop the service. The service status MOOC that a disabled Service will not be started automatically at boot or by other unit pipes, but can be started many ways. Creating an alias for system CTL commands. If you frequently use any of the previous commands, you can create an alias command in your home base RCP. Two, easily invoke it. For example, to add an alias for the command used for showing the running services. You can do the following. First, well-being the dot push RC file. You can choose your preferred text editor, like them, or nano. Restart the terminal. Let's try using the new ideas. You can use the running underscore services command to view a list of all loaded activity running services on your system. Thanks for viewing.