Summary of "The 50 Most Popular Linux & Terminal Commands - Full Course for Beginners"

This comprehensive beginner-friendly course by Colt Steele covers essential Linux and terminal commands that are foundational for developers, sysadmins, and anyone working in tech fields involving Unix-like environments (Linux, macOS, WSL on Windows). The course blends practical command usage with conceptual understanding of operating systems, shells, permissions, and file management.

Main Ideas, Concepts, and Lessons

1. Introduction & Context

Instructor Colt Steele introduces himself and credits Flavio Copez for the Linux Commands Handbook used as a resource.
Emphasis on learning Linux commands as essential for tech careers (web dev, devops, data science, security, AI, etc.).
Commands covered work on Linux, macOS, and WSL on Windows.
Explanation of why command line skills matter: speed, control, automation, universality.
Overview of Unix, Linux, macOS, and Windows OS lineage, showing why Linux/macOS share commands but Windows differs.
Explanation of shells (bash, zsh, fish), terminals, and how commands are interpreted.

2. Setup & Installation

How to access terminal on Linux (Ubuntu), macOS, and Windows (using Windows Subsystem for Linux - WSL).
Instructions for installing WSL on Windows 10/11, running Ubuntu terminal, and optionally Windows Terminal app for better experience.
Explanation of running commands in the appropriate shell environment (bash or zsh).

3. Basic Commands & Navigation

whoami: Prints current logged-in username.
man: Access manual pages for commands; navigation inside man pages (q to quit, space to scroll).
clear / Ctrl+L: Clear terminal screen.
pwd: Print current working directory.
ls: List directory contents; options like -l (long format), -a (show hidden files), combining options (-la).
cd: Change directory; relative paths, absolute paths, .. to go up one directory, ~ for home directory.
Explanation of folder structure: root /, home directories /home/username, importance of absolute vs relative paths.

4. File & Directory Management

mkdir: Create directories; options like -p to create nested directories.
touch: Create empty files or update timestamps of existing files.
rm: Remove files; rm -r to remove directories recursively; rm -i for interactive deletion.
rmdir: Remove empty directories only.
mv: Move or rename files/directories.
cp: Copy files or directories (-r for recursive).
open (macOS) and xdg-open (Linux): Open files/folders in graphical apps.

5. Viewing & Manipulating File Contents

head / tail: View first/last lines of a file; tail -f to follow live updates (e.g., logs).
date: Print current date/time; used to demonstrate output redirection.
Output redirection:
- > overwrites file.
- >> appends to file.
cat: Concatenate and display entire file contents; can combine multiple files and redirect output.
less: Interactive file viewer with scrolling and searching (/ to search, q to quit).
echo: Print text or redirect text into files (quick file creation or appending).
wc: Word, line, byte count of files or piped input.
Piping (|): Pass output of one command as input to another (e.g., ls | wc -l to count files).
sort: Sort lines alphabetically or numerically; options for ignoring case, uniqueness (-u).
uniq: Filter adjacent duplicate lines; often combined with sort.
Shell expansions:
- Tilde ~ expands to home directory.
- Wildcards *, ? for pattern matching filenames.
- Curly braces {a,b,c} for generating multiple strings/files.
diff: Show differences between two files; options for side-by-side (-y) and unified diff (-u).

6. Searching & System Information

find: Search files/directories by name, type, size, modification time; can execute commands on results with -exec.
grep: Search text inside files; supports regular expressions, recursive search (-r), case-insensitive (-i), line numbers (-n).
du: Disk usage of files/directories; options for human-readable sizes (-h), sorting output.
df: Disk free space and usage of mounted filesystems; human-readable option.