Master Linux Troubleshooting: Hands-On Training for 2026 Pro

Master Linux administration, troubleshooting, shell scripting, security, networking, storage management, and real-world enterprise Linux skills through practical hands-on labs.

This course is designed to help students, system administrators, DevOps engineers, cloud professionals, and IT beginners build strong practical Linux skills from the ground up.

My name is Shikhar, and I’ll be your instructor throughout this journey into the world of Linux, system administration, troubleshooting, automation, shell scripting, networking, security, and enterprise-level server management.

In this course, you will learn Linux from the ground up with a strong focus on practical implementation, hands-on labs, and real-world industry scenarios.

Introduction to Linux: Basic Concepts and History of Unix/Linux

· Course Module Overview

· Understanding Unix: A Brief Introduction

· The Evolution of Linux: A Historical Perspective

Understanding Linux Filesystem & OS Installation

· Exploring the Linux Filesystem

· Understanding File Types in Linux

· Essential Downloads: RHEL, CentOS & Virtualization Tools

· Installing Linux on a Virtual Machine

· Connecting to Linux Using PuTTY

CentOS 10 Installation on Oracle VirtualBox – Complete Guide

· An Overview of This Section

· Download and Install VirtualBox

· Download CentOS 10 ISO

· Create a New Virtual Machine

· Configure the Virtual Machine

· Configure Virtual Hardware

· Hard Disk File Type and Format

· Uncheck - Proceed with Unattended Installation

· Begin the Installation

· Configure Installation Summary

· Log in to the CentOS Desktop Environment

· Access Linux VM from Windows using MobaXterm

· Login Issue Troubleshooting

Step-by-Step Guide to Installing CentOS 9 on Oracle VirtualBox

· Overview of Steps to Install CentOS 9 on Oracle VM

· Download and Install VirtualBox

· Download CentOS 9 ISO

· Create a New Virtual Machine

· Configure the Virtual Machine

· Start the Installation

· Install MobaXterm and PuTTY to access the virtual machines

· Access the virtual machine using MobaXterm and PuTTY

Linux Commands Tutorials

· In-depth lectures on essential Linux commands, demonstrated with real-time examples in a live environment.

· Overview of the Linux file system structure to understand directory hierarchy and navigation.

· Practical usage and explanations of commonly used commands, including:

pwd, cd, ls, less, cp, file, mkdir, more, mv, cat, rm, rmdir, wc, dd, head, tail, touch, ln, and more.

Understanding the Linux Filesystem Hierarchy

· What You Will Learn in This Section

· Linux Filesystem Explained

· Understanding Disk-Based Filesystems

· Memory-Based (tmpfs) Filesystem

· Understanding the Root ( / ) Filesystem in Linux

· Understanding devtmpfs Filesystem in Linux

· Understanding tmpfs Shared Memory Filesystem in Linux

· Understanding tmpfs Mounted on /run

· tmpfs Filesystem for systemd-journald Service

· Understanding the /boot Filesystem in Linux

· Understanding /run/user tmpfs Filesystem

Bash Profile, Variables, and Standard I/O Redirection

· Understanding the User's Home Directory

· Overview of .bash_profile, .bashrc, and .bash_logout

· Setting and Modifying the PATH Variable in .bash_profile

· Introduction to Bash Variables

· Environment and System Variables Explained

· Distinguishing Between Bash, Environment, and System Variables

· Practice Lab: Working with Different Types of Variables

· Understanding Standard Input, Output, and Error Streams

· Redirecting Input and Output Using >, 2>, &>, and More

· Lab: Practical Exercises on Variable Use and I/O Redirection

Linux User Administration: Best Practices

· Overview of User Administration

· Different User Account Types

· User Administration Files

· User Account Creation

· Configuring a User Account with Custom Attributes

· Linux User Groups: Primary vs. Secondary

· Usermod - Managing User Accounts

· Modifying User Account Groups in Linux

· Modify a User's Home Dorectory in Linux

· Modify a User's Shell in Linux

· Set Accout Expiration Date

· Overview of Shadow File

· Structure of the Shadow File

Managing User Password Expiration with the Chage Command

· Overview of Chage Command

· Set Minimum Password Age with Chage

· Set Maximum Password Age with Chage

· Set Password Warning Period with Chage

· Set Password Inactivity Period with Chage

· Set Account Expiration with Chage

· Configure Global Password Aging Policies

· Troubleshooting user and Group Issues in Linux

Permissions in Linux

· Understanding Basic File Permissions

· User, Group, and Others: Permission Categories

· Types of Permissions: Read, Write, Execute

· Changing Permissions and Ownership

· Special Permissions in Linux

· Setuid, Setgid, Sticky Bit, and ACL Explained

· Lab 1: Real-World File Permission Tasks

· Lab 2: Advanced Permission Scenarios from Industry

Managing File Access with ACLs (Access Control Lists)

· Introduction to ACL Concepts

· Setting ACLs on Files

· Understanding and Configuring Default ACLs

· Lab: Apply ACLs to Files

· Lab: Apply ACLs to Directories

· Lab: Using Mask to Restrict Permissions

· Lab: Working with Default ACLs

· Practice Exercise: Scenario-Based Task on ACLs

Managing sudo Access with visudo

· Basics of sudo and privilege management

· Using aliases in the sudoers file

· Understanding and editing the sudoers configuration

· Common sudo command examples

· Practice Lab: Set up and test sudo access

Linux Crontab

· Overview of Linux Crontab & its format

· Schedule a job for a specific period of time

· Schedule a job for more than one instance (e.g. twice a day)

· Schedule a job for a specific range of time

· Schedule a job every weekday during working hours

· how to view crontab entries?

· Schedule a job for every minute using cron

Linux Find Commands

· Basic find commands for finding files with names

· Find files based on their permissions

· Search files based on owners & groups

· Find files and directories based on date & time

· Find files and directories based on size

OpenSSH: Concepts and Hands-on Labs on CentOS 10

· Overview of OpenSSH

· Why OpenSSH Is Important

· SSH vs Telnet

· Key Features of OpenSSH

· Overview of OpenSSH Lab

· OpenSSH Lab: Check Package, Port & Version

· OpenSSH Lab: SSH Config File & Directory

· OpenSSH Lab: SSH Service Management

· OpenSSH Lab: Remote SSH Connection

· OpenSSH Lab: Change Default SSH Port

· OpenSSH Lab: Disable Root Login

· OpenSSH Lab: SCP File Transfer

· OpenSSH Lab: SFTP File Transfer

Process Management

· Understanding ps commands with custom properties & Nice values etc

· Different stats of a process like "D", "S", "T", "Z" etc

· Kill commands to terminate the process

· Lab

Kernel Modules

· What is Kernel & its features

· Kernel Modules

· Commands to manipulate the kernel (insmod,lsmod,modinfo,modprobe &rmmod)

· How to know the name of the module or kernel driver for any device like lan

· Lab

Disk Partitions, File Systems Creations & RAID Configuration

· Creating the partitions in a simple disk using fdisk

· Understanding the different options in fdisk utility

· Creating File Sytems using (ext3/ext4/xfs FS)

· Mounting/Umounting FS

· Entry in fstab

· Introduction to RAID

· Concepts & features of RAID

· RAID Level

· How to configure the different levels of Raids like (0,1,5,6, 10, etc.)

· Lab Sessions

Logical Volume Manager Administration

· LVM Architecture Overview

· LVM Components

· LVM Logical Volumes

· Logical Volume Creation Overview

· Growing a File System on a Logical Volume

· Logical Volume Backup

· LVM Administration with CLI Commands

· Using CLI Commands

· Physical Volume Administration

· Creating Physical Volumes

· Displaying Physical Volumes

· Preventing Allocation on a Physical Volume

· Resizing a Physical Volume

· Removing Physical Volumes

· Volume Group Administration

· Creating Volume Groups

· Adding Physical Volumes to a Volume Group

· Displaying Volume Groups

· Removing Physical Volumes from a Volume Group

· Changing the Parameters of a Volume Group

· Activating and Deactivating Volume Groups

· Removing Volume Groups

· Overview of LVM Metadata

· Metadata Contents

· How to identify and recover failed LVM disk

RPM (Red Hat Package Manager)

· Install: It is used to install any RPM package.

· Remove: It is used to erase, remove or un-install any RPM package.

· Upgrade: It is used to update the existing RPM package.

· Verify: It is used to query about different RPM packages.

· Query: It is used for the verification of an RPM package.

YUM (Yellowdog Updater, Modified)

· Overview of YUM

· Configuration& and installation of yum on Red Hat Linux Server

· Lab-1

· Lab-2

· Yum History Command

· Reverting and Repeating Transactions like undo & redo using yum command

Linux Boot Process (CentOS 10 / RHEL 10)

Rescue and Emergency Mode in Linux

· Linux Emergency Mode: Overview and Use Cases

· Steps to Boot into Emergency Mode in Linux

· Lab: Boot into Emergency Mode and Fix Issues

· Linux Rescue Mode: Overview and Use Cases

· Steps to Boot into Rescue Mode in Linux

· Lab: Boot into Emergency Mode via GRUB (Edit Method)

· Lab: Boot into Emergency Mode Using CentOS ISO Image

Initramfs File Missing – Diagnosis & Fix

· Scenario Overview

· Simulating the Failure: Missing Initramfs

· Recreate Initramfs from Rescue Mode

GRUB Configuration File Missing – Diagnosis & Fix

· Scenario Overview

· Simulating the Failure: Missing GRUB Configuration File

· Manual Boot from GRUB Prompt

· Recreating GRUB Configuration Using grub2-mkconfig

BIOS Boot Partition Corrupted – Diagnosis & Fix

· Understanding the BIOS Boot Partition

· Identify BIOS Boot Partition

· Corrupt BIOS Boot Partition Using dd (Simulate Failure)

· Fix Boot Failure: Reinstall GRUB from Rescue Mode

Missing Critical Binary (/bin/mount) – Diagnosis & Fix

· Scenario Overview

· Simulating the Failure: Missing /bin/mount Binary

· Recover /bin/mount via Package Reinstall (Rescue Mode)

Kernel Missing/Corrupted – Diagnosis & Fix

· Simulating the Failure: Missing Kernel File

· Fix Boot Failure: Reinstall Kernel from Rescue Mode

Root Filesystem Not Found – Diagnosis & Fix

· Simulating the Failure: Modify Root Entry in Boot Configuration File

· Reboot and Observe the Failure

· Fix: Modify Root Entry from GRUB Prompt

/etc/fstab Misconfiguration – Diagnosis & Fix

· Scenario Overview

· Simulating the Failure: Incorrect /etc/fstab Entry

· Fix Boot Failure from Emergency Mode

Linux OS Minor Upgrade

· Linux OS upgrade from RHEL 7.1 to RHEL 7.2

· Lab Practice Sessions

File Transfer Protocol

· Overview of FTP Server

· Installation and configuration of FTP Server

· Lab-1

· Lab-2

Apache Web Server Administration

· Basic Setup

· Verify installation

· Package files

· Main configuration file(s)

· Backup

· Edit the httpd.conf configuration file

· ServerRoot

· PidFile

· ServerName

· Add site to the host's file

· DocumentRoot

· ErrorLog

· Listen

· Create your HTML documents

· Start the Web Server

· Access the website

· Local access

· Internal & external access

· Summary of basic setup

DNS (Domain Name System)

· Overview of DNS

· Understanding root & top-level domains

· How DNS works practically

· What happens when I type any website name in the address bar of the browser

Samba Server

· Overview of Samba Server

· Features of Samba Server

· How Samba Server Works

· Samba File sharing Server

· CIFS File System

· Practice Lab Sessions

Postfix Mail Server Configuration

· The structure of the Email System

1.1 Mail User Agent

1.2 Mail Transfer Agent

1.3 Mail Delivery Agent

1.4 SMTP

· Configuring an RHEL Email System

· Postfix Pre-Installation Steps

· Installing Postfix on RHEL 7

· Configuring Postfix

· Starting Postfix on an RHEL System

· Configure a Null Client

· Relayhost

· Introduction Dovecot, Imap & pop3

· Configuring Dovecot

· Thunderbird - Mail User Agent (Configure Mail Box)

Securing & hardening a Linux System

· Linux Physical Security

· How to break root password

· Securing the grub menu

· Reset root password from rescue mode

· BIOS Protection

· General Security

· Keep your system updated

· Turn off IPv6

· Disable USB Stick to detect

· Restrict Users to Use Old Passwords

· Check Password Expiration of a User

· Password Expiration - Lab Session

· Verify accounts for an empty password

· Verify accounts with "Zero" UID

· Review logs regularly

· Keep /boot as read-only

Managing Server Firewalls

· Firewall concepts

· About nftables, features, and advantages of firewalld

· Firewalld components, pre-defined zones

· How packet flows through the firewall

· Check firewalld services - Lab Session

· Adding and Removing Services & Port from Firewall Server - Lab Session

· Add Services Permanently in Firewalld - Lab Session

· Add HTTP Service in firewalld - Lab Session

· Port forwarding - Lab Session

· Conceptual discussion about Masquerading, Packet Flow in Firewalld

· Masquerading with Port Forwarding - Lab Session

· About Rich Rules in Firewalld

· Specifically allow a Server using Rich Rules - Lab Session

· Allow Telnet Port, SSH with log-prefix using Rich Rule - Lab Session

· Accept, Reject, Drop - Lab Session

Network File System (NFS) on Linux

· Overview of NFS Server

· Installation and configuration of NFS Server

· Lab-1

· Lab-2

Automating Installation using Kickstart

· Overview of Kickstart Server

· Features of Kickstart Server

· Configuration & Installation of Kickstart Server

· Configuration of dhcp, tftpd, nfs for Kickstart Server

· Configuration of kickstart config file using graphical mode

· PXE Boot Environment

· Lab Session

· Unattended Client boot and do the installation via network

Networking Concepts in Linux

· New Sets of commands introduced in RHEL 7 for managing the network interfaces.

· Check the status of ethernet interfaces

· Add and configure the new ethernet interface

· Activate the network services

· Commands to change the network properties of an existing interface

· Delete the ethernet interface

· Learning various new commands related to managing network interfaces.

· Overview of Routing Table

· Understanding the output of netstat -rn or route -n output

· Lab

Linux Performance Monitoring

· Introduction about Performance monitoring in Linux

· Important four subsystems that need to be monitored.

1. CPU
2. Memory
3. IO
4. Network

· Familiar & understanding with CPU Utilization

· Like Context switches, Run Queue, CPU utilization & Load Average

· Familiar & understanding with Memory Utilization

· Familiar & understanding with I/O Analyses

· Familiar & understanding with Network Monitoring

· Familiar with various Commands to manage performance issues in Linux Servers

· top

· vmstat

Managing SELinux Security

· Introduction - SELinux

· SELinux Security Concepts

· Changing SELinux Modes

· Practice Lab Sessions

· Changing SELinux Contexts

· SELinux Booleans

· Audit logs & troubleshooting SELinux

Backup and Restore

· Overview of Backup

· Various commands for backup

· Types of backup

· Full backup, Incremental backup, and differential backup

dump command to take backup & restoration

Advanced Linux Commands

· dig, nslookup, rsync, scp, ssh, sftp, find, grep, locate, df, du, lsof, ps, top, who,cut, sort, vi, sed, awk, tar, gzip, bzip2 etc

· useradd, userdel, usermod, groupadd, groupdel, id, chage, chroot, chown etc

· mount, umount, fdisk, mkfs, fsck,/proc, uptime etc

· ping, nslookup, telnet, ifconfig, ifconfig-a, netstat -a etc

· systemctl -at service, systemctl -t service --state=active, systemctl start name.service, systemctl enable name.service etc

· pvs, vgs, pvdisplay,lvs, lvdisplay, pvcreate, pvremove, vgcreate, vgrename, vgremove, vgextend, vgreduce, lvcreate, lvextend, lvreduce,fdisk, vgexport, vgimport, vgcfgrestore, vgcfgbakcup, watch, whoami, passwd, su etc.

Linux Bash Shell Scripting: A Practical way of Learning

Introduction of Shell Programming

· What is Bash Shell?

· Types of Shell available in Linux

· About Shell Scripting

· Bash Shell Startup Scripts

· User’s Home Directory - .bash_profile, .bashrc & .bash_logout

· Shebang

· Create a simple Shell Script

· Setting up permissions on a script

· Debug a Script

The Shell Variables & Environment

· Bash Variables

· Environmental Variables

· System Variables

· Assign values to shell variables

· Customize the bash shell environments

· set, env & export command

· Rules for naming the variable name

· Simple Script using the echo command

· Quoting

· There are three Type of quoting

· The double quote

· The single quote

· The Backslash

· User's Input via Keyboard

· Read Command

· IFS

· Practice Lab Session

Arithmetic Operations

· Performing Arithmetic Operations

· Create an integer Variable

· Create the Constants Variable

· Path name expansion

· Wildcards [*], ?, [..] etc

· Create & use aliases

· Practice Lab Sessions

Industrial Project to Completely Automate the Pre-validation report

· A Shell Script to collect the required information from a server

· The Bash Color

· Writing Color Text

· Various Color Codes for Foreground & Background Text

· Lab Session on Bash Color

· Script to fetch the system information i.e system_details

· Schedule the script via cron

· Final Script to fetch the environment report with a single click

· Lab Session

Conditional Statements (Decision Making)

· Overview of conditional execution

· What is Condition?

· Boolean value (True & False)

· If else statement

· Lab Session on if..else..

· if..elif..else..fi statement

· test command

· Logical AND &&

· Logical OR !!

· The exit status of a command

· Numeric Comparison

· String Comparison

· File Attributes Comparison

· Shell Command line parameters

· Positional parameters via special shell variable

· Practice Lab Session

Bash Loops

· Overview of loop statement

· for loop statement

· Lab on for loop

· for loop using C like Syntax

· for loop using command-line arguments

· Nested for loop statement

· Chessboard using a nested loop statement

· While loop statement

· Lab Session - read a text file line-by-line or using IFS

· infinite while loop

· case statement

· Lab session on case statement

· Create a simple menu-driven program or automation tool Using Case Statement

· Industrial Project

· Discussed various scripts using for or while loop

Shell Redirection & Process Management

· Input Output Redirection in Linux

· Lab Session on redirection

· Pipelines in Linux

· tee command

· file descriptor (fd) to file for output

· file descriptor (fd) to file for input

· file descriptor (fd) for reading & writing

· Practice Lab Session

· Overview of a Process

· Foreground & background Process

· Various Stats of a process

· Lab Session

Functions

· Defining functions

· Displaying functions

· Nested functions

· Lab Session - writing functions

· Calling functions

· Local & global variables

· Passing arguments into a function

· return statement

· Practice Lab Sessions

AWK

· Introduction Awk

· Pattern matching

· User-defined variables in awk

· Awk pre-processing

· Awk post-processing

· Practice Lab Session

SED Stream Editor

· Introduction

· Replacing or substituting string.

· Replacing the nth occurrence of a pattern in a line

· Replacing all the occurrence of the pattern in a line

· Changing the slash (/) delimiter

· Using & as the matched string

· Duplicating the replaced line with /p flag

· Replacing string on a specific line number

· Replacing string on a range of lines

· Replace on lines which match a pattern

· Deleting lines

· Add a line after a match

· Add a line before a match

· Last Lecture