Linux Basics and Fundamentals

This tutorial provides a foundational understanding of core Linux management concepts. It focuses on the Linux file system, handling packages on Debian-based systems, managing services with systemd, and monitoring processes. These practical areas are essential for anyone working with Linux in a system administration or support capacity.

Linux File System Hierarchy Overview

The Linux File System Hierarchy organizes files logically within the Linux system, essential for administration, troubleshooting, and software management.

• /: Root directory
• /bin: Essential user binaries
• /sbin: System maintenance binaries
• /boot: Boot loader files
• /etc: System-wide configuration files
• /home: User directories
• /lib, /lib64: Shared libraries
• /usr: User-installed applications
• /var: Variable data like logs and databases
• /tmp: Temporary files
• /opt: Optional third-party software
• /dev: Hardware device files
• /proc, /sys: Virtual filesystems for real-time system information
• /mnt, /media: Mount points for external filesystems and removable media

Package Management on Debian-based Systems

Debian-based systems utilize APT (Advanced Package Tool), managing software through repositories hosting pre-compiled software packages.

• Repositories: Managed through /etc/apt/sources.list and additional PPA repositories.
• Key APT commands:
  • apt update: Refresh package lists
  • apt upgrade: Upgrade installed packages
  • apt install: Install new packages
  • apt remove: Uninstall packages, leaving configuration files
  • apt purge: Completely remove packages and configurations
  • apt search: Search available software

dpkg (Debian Package): Low-level package manager used for installing, removing, and managing .deb packages directly.

• Install: dpkg -i package.deb
• Remove: dpkg -r package_name
• Purge: dpkg -P package_name
• List installed packages: dpkg -l

Managing System Services

systemd is the default initialization and service manager system in modern Linux distributions. It handles startup and management of system services through units and targets.

• Status: systemctl status <service>
• Start/stop/restart: systemctl start|stop|restart <service>
• Enable/disable auto-start: systemctl enable|disable <service>
• Logs: journalctl -u <service>

Process Management

Processes are active executing programs managed by the Linux kernel, identified by unique PIDs, resource allocation, and scheduling.

• View: ps, top, htop
• Terminate: kill <PID>, pkill <process_name>
• Background/foreground: bg, fg, jobs

System Monitoring and Logging

• uname: Kernel info
• hostnamectl: Hostname management
• lscpu: CPU info
• free: Memory usage

Logging Directories: /var/log/syslog, /var/log/auth.log, /var/log/dmesg

Conclusion

This tutorial introduces the essential skills for managing a Linux environment. From understanding the file system hierarchy to installing packages, controlling services, handling processes, and writing shell scripts — these foundational practices are critical for effective Linux system administration. Mastery of these topics enables greater confidence in real-world IT environments where Linux plays a central role.