Linux Administration

This is a comprehensive summary of the core concepts from the Linux Foundation - (LFS101) exam. This section includes embedded slides and a detailed breakdown of key topics such as Linux History, Linux architecture, Linux management, and security. Ideal for beginners preparing for Linux Foundation - (LFS101) certification or anyone looking to understand the basics of Linux Fundamental.

🐧 Linux Fundamentals & System Architecture

📘 1. Introduction to Linux

• History and philosophy of Linux and open source
• Common distributions and their package managers (RPM/DEB)
• Kernel vs. user space

📁 1.2. Linux Filesystem Hierarchy

• Understanding of /, /home, /etc, /var, /tmp, /usr, /bin, /sbin
• Navigating directories using cd, ls, pwd, find, and locate

💻 2. Command Line Skills

2.1. Shell and Terminal Usage

• Understanding bash and shell environments
• Command structure and usage of options/arguments
• Input/output redirection (>, >>, <, |)
• Command substitution and quoting

2.2. File Management

• File and directory operations: cp, mv, rm, mkdir, rmdir, touch
• File permissions: chmod, chown, umask, symbolic vs. numeric
• Links: hard vs. symbolic links

2.3. Text Processing Tools

• cat, head, tail, less, more
• grep, cut, awk, sed, sort, uniq, wc

👥 3. Users and Permissions

3.1. User and Group Management

• Create, modify, delete users and groups
• Understanding /etc/passwd, /etc/shadow, /etc/group
• Use of useradd, usermod, groupadd, passwd, who, id, su, sudo

3.2. File Permissions and Ownership

• Reading file permission notation
• Modifying permissions for user, group, others
• Understanding SUID, SGID, sticky bit

⚙️ 4. System Services and Processes

4.1. Process Management

• Understanding foreground/background jobs
• Using ps, top, htop, kill, nice, renice, jobs, fg, bg

4.2. System Logging

• Understanding log files in /var/log/
• Use of dmesg, journalctl, logger

4.3. Service Management (init/systemd)

• Starting, stopping, restarting services
• Enabling/disabling at boot
• Checking status: systemctl, service, init.d

📦 5. Package Management

5.1. RPM-based Systems

• Use of yum, dnf, rpm

5.2. DEB-based Systems

• Use of apt, dpkg

5.3. General Concepts

• Installing, updating, removing packages
• Managing repositories

🌐 6. Networking and Security

6.1. Basic Networking

• Network configuration files
• Use of ip, ifconfig, ping, netstat, ss, traceroute, dig, nslookup

6.2. Secure Shell (SSH)

• Using ssh, scp, rsync
• Generating and managing SSH keys
• Remote login and file transfer

6.3. Firewall and Security Basics

• Basic concepts of firewalls (iptables, ufw)
• File integrity and audit (auditd)
• Setting up simple access control

💾 7. Storage and Filesystems

7.1. Disk and Filesystem Management

• Partitioning with fdisk, parted
• Formatting with mkfs
• Mounting and unmounting devices (mount, umount)
• fstab configuration

7.2. Filesystem Maintenance

• Checking disk usage: df, du
• Checking and repairing file systems: fsck, tune2fs

⚡ 8. Scripting and Automation

8.1. Shell Scripting Basics

• Writing basic bash scripts
• Variables, conditionals, loops
• Executing and debugging scripts

8.2. Cron and Scheduled Tasks

• Creating cron jobs using crontab
• Using at and anacron
• Understanding cron syntax

🔄 9. System Boot and Runlevels

9.1. Boot Process

• BIOS to bootloader (GRUB)
• Kernel loading and init/systemd
• Troubleshooting boot issues

9.2. Runlevels and Targets

• Understanding systemd targets
• Switching targets with systemctl isolate

🔍 10. Troubleshooting and Diagnostics

10.1. System Monitoring

• Monitoring CPU, memory, disk, and processes
• Identifying performance bottlenecks

10.2. Log Analysis

• Understanding and analyzing system logs
• Troubleshooting common issues (boot, network, service)