Linux Fundamentals and Features

Linux Fundamentals

• APNIC presented information on Linux fundamentals.
• The kernel is the core of the operating system.
• "Linux" refers to a group of operating system distributions built around the Linux Kernel.
• Linus Torvalds developed the Linux Kernel.
• Kernel version 0.01 was released in September 1991.
• Major release version 1.0.0 was released in March 1994.
• The latest kernel release is version 5.8.7 (05-09-2020).

Key Features of Linux

• Kernel acts as the core component.
• Open-source.
• Multi-user capability and multitasking.
• Hierarchical file system.
• Portable.

Linux Distributions

• Many Linux distributions exist, each with its own features and branding.
• Examples include Mandriva, SUSE, Ubuntu, Kubuntu, Archlinux, Gentoo, Slackware, CentOS, Debian, Fedora, Xubuntu, Linux, KATOOS, and Edubuntu.

The Shell

• The shell is a command interpreter, not part of the kernel.
• It uses the kernel to execute programs, create files, and more.
• Several shells are available, including Bash, Csh, Ksh, and Zsh.
• echo $SHELL can be used to determine the current shell.

Linux-Based OS Architecture

• User space handles user applications.
• Libraries are used for functionalities.
• System daemons manage system tasks.
• Shared libraries offer shared functionalities.
• Shells execute commands.
• Tools provide necessary functions for applications.
• Kernel space has the Linux kernel, including scheduler, drivers, security, and networking.

Directory Structure

• The Filesystem Hierarchy Standard (FHS) defines directory structure and contents in Linux distributions.
• All items reside under the root directory (/).
• Directories like /bin, /sbin, /etc, /dev, /var, /tmp, /home are common.

Directories (Examples)

• / – Represents the root.
• /bin – Stores user-level binary files.
• /sbin – Stores system binary files/executables.
• /etc – Stores configuration files.
• /dev – Stores device files.
• /var – Stores variables and files that grow.
• /tmp – Stores temporary files.
• /home – Stores user home directories.

Users and Groups

• Linux uses two main user types: System and Regular users.
• Superusers (root) have full access and control over system-wide changes.
• /etc/passwd lists all users and their details.
• Groups are collections of users with shared permissions.
• /etc/group lists group information.

Ownership and Permissions

• Linux uses a standard set of permissions for files and directories.
• Access permissions control file and directory access.
• Ownership and permissions can be changed using commands like chown, chgrp, chmod.
• ls -lah command to view files and directories.

Permissions Set

• Permissions define read, write, and execute access levels.
• Different permissions apply for files and directories.

Bash Scripts

• Bash scripts are plain text files that contain commands.
• Users can create commands in scripts.
• Scripts are used in automating commands.
• Example: #!/bin/bash\necho "Hello World"

CRON - Task Schedule

• CRON is a task scheduler in Linux.
• It runs commands at predetermined times.
• Examples include sending emails, backing up data, and updating with security patches.
• Useful in automating tasks.

Text Editor(s)

• Text editors are programs used for editing files.
• Configuration files or text files are often edited on Linux.
• Many editors are available, including command-line editors like vi, nano, pico, and GUI editors like gedit and KWrite.

man Pages

• Man pages are documentation for various commands and programs.
• Users can use the man command to access them from the command-line interface (CLI).
• Example: man ifconfig provides details on ifconfig.

This quiz delves into the fundamentals of Linux, covering key concepts such as the Linux kernel, its history, and its open-source nature. You will explore various Linux distributions and understand the shell's role in executing commands and managing files. Test your knowledge of this popular operating system and its core components.