Ultimate Linux Guide with Interview Preparation

From Unix origins to the Linux kernel, learn why Linux emerged as a free, Unix-like, open source alternative and how distributions form the GNU/Linux system.

Compare Linux and Unix: Linux is open source and free, developed since 1991 for desktops and mobiles, while Unix is licensed and non open source, mainly for servers and workstations.

Explore the Unix and Linux architecture, from application programs and the shell to the kernel and hardware, and see how memory management, task scheduling, and the file system interact.

Explore the Linux directory structure from the root, and learn where essential binaries, configuration files, device files, process information, user homes, boot, libraries, optional apps, and mount points live.

Learn the basics of Linux commands, including cd, pwd, and cat, and understand environment variables and the PATH variable that determines where the system searches for executables.

Master basic linux commands like pwd, cd, ls, and cat to navigate the home directory and view files, then discover man, clear, and which to access documentation and locate binaries.

Explore linux directories with absolute and relative paths, using dot and dot dot, slash, and tilde for home; master cd, pwd, mkdir, and rmdir, including recursive removal.

Learn to navigate Linux directories using absolute and relative paths, cd commands including cd - and . and .., and basic management with mkdir and rm -rf.

Master listing files with ls, interpret the long list format, reveal hidden files, and sort by last modified time using a single dash combination like -lhd.

Master the ls command with options to show hidden files, long listing with permissions and dates, human-readable sizes, and sorting by time or name for administrators and DevOps tasks.

Learn the links command in Linux and distinguish hard links from symbolic (soft) links, with practical examples. Understand inodes as a data structure that stores file attributes and disk locations.

Explore links and shortcuts in Linux hands-on, using hard and soft links to connect files and directories, with Windows shortcut analogies and absolute paths.

Explore Linux file and directory permissions, including owner, group, and others, with read, write, execute, and special setuid, setgid, and sticky bits; view with ls -l and modify with chmod.

Describe Linux file and directory permissions, including owner, group, others, and read, write, execute bits; show chmod, chown, and chgrp usage, plus directories, sticky bit, and root access basics.

master practical file and directory searching in linux using find, locate, and related options, including case-insensitive name matching, exec actions, and updating the locate database.

Explore viewing and editing files with the nano editor, using commands to display the first or last lines with dash options, and to open a file to create or edit.

Learn to view files efficiently using cat, more, and less, and monitor logs in real time with tail. Explore nano basics, including editing, searching, replacing, undo/redo, and exiting with ctrl-x.

Contrast vi, vim, and view as editors, noting vim is vi improved and view provides read-only mode, and outline essential vim shortcuts for navigation, editing, saving, quitting, and searching.

Learn vi/vim hands-on to edit files, switch between read-only view and insert mode, navigate lines, use visual mode for copy and paste, search and replace, and save or quit.

Learn to copy, move, and rename files in Linux using cp and mv, delete with rm -rf or rm -f, and use wildcards with caution, while creating files with touch.

Master file descriptors in Linux, including standard input (0), standard output (1), and standard error (2). Explore redirecting streams with >, >>, and < to files or input sources.

Practice redirecting command output to a text file, appending to it, and feeding input from a file, and learn standard error redirection to the null device.

Learn to compare files on linux with diff, sdiff, and vimdiff, using side-by-side views that highlight edits and differences between left and right files.

Learn how to transfer files over the network using scp in Linux. Copy between local and remote servers with key-based authentication, specifying source, destination, and optional names.

Discover how to create and use shell aliases, persist them in bashrc and profile, and manage aliases across login and non-login shells.

Identify environment variables and how they differ from normal variables, then define them for a user or system using profile files and the source command.

Explore processes and job control in Linux, using an interactive process viewer to manage foreground and background tasks, view and control jobs with bg/fg, suspend, and kill with signals.

Master Linux process and job control: view processes with ps and top, run background tasks, and manage with fg, bg, jobs, and signals like 15 and 9.

Learn to schedule tasks with cron in Linux using crontab commands to install, list, edit, and remove jobs, and understand minutes, hours, day of month, month, and day of week.

Learn to schedule, view, edit, delete, and manage cron jobs for users with crontab, including schedules like every minute or every day at 8 a.m.

Learn how to view command history, locate the history file, adjust history size and history file size in bash, and secure credentials by managing history.

Explore how sudo allows a permitted user to execute commands as root or another user, how sudoers and groups grant access, and the risks of misconfiguring root privileges.

Master linux user and group management with hands-on steps for adding users, assigning sudo privileges, inspecting groups and shadow files, and safely deleting users with home directories.

Explore how bios loads the master boot record and grub, then the kernel, root file system, initial ram disk, and systemd targets, with runlevels and rc.d startup and shutdown programs.

Master linux file system basics with df and du for disk usage, and ls and pwd to locate files. Understand absolute versus relative paths, dot and dot dot, and mounting.

Explore shell scripting basics for beginners, including the Unix shell, variables, operators, and case statements. Learn how comments describe steps and how loops with functions fit into scripts.

In this lecture on Linux operators, learn how to assign values in the shell, use the expr command for arithmetic, and perform addition, subtraction, multiplication, division, and modulus with spacing.

Explore loops in scripting, including for and while loops, with syntax demonstrations, and break and continue usage.

Explore shell variables, including special parameters like the script name and positional arguments. Create and run executable scripts with a shebang, and manage exit statuses and background processes.

Explore function concepts with a simple hello function, showing how to define and call it by name to print hello world, linking to programming basics.

Explore shell decision making with if else and case in bash, covering string and numeric comparisons (-eq, -ne, -lt, -le, -ge) and case-based fruit examples.

Explore Linux interview fundamentals, including its Unix-based kernel and open-source nature, and learn the core components such as shells, gui, and system utilities.

Practice Linux interview questions in part two, covering renaming files with mv, inodes, process IDs, distro variants like Red Hat, Debian, Fedora, plus swap space, Bash, and command line interface.

Explore Linux interview preparation part 3 to review Linux virus myths, locate system configuration files, master compression and redirection, and use vi editing shortcuts and grep pattern searches.