FreeCodeCamp Linux Command Line Full Course
by William E. Shotts, Jr.
FreeCodeCamp is known for its high-quality, in-depth tutorials. Their Linux command line full course on YouTube is a highly recommended resource for beginners to get a solid foundation.
More resources on Linux Command Line
Advanced Bash-Scripting Guide
This is a detailed and well-structured PDF guide from the Linux Documentation Project, offering an in-depth look at Linux shell scripting, which inherently covers many advanced command-line concepts.
LearnLinuxTV
This YouTube channel offers a wide range of Linux tutorials, including many focused on the command line. The content is practical and well-explained, suitable for various skill levels.
Linux Journey
A popular and free interactive online course that teaches the fundamentals of the Linux command line. It's structured with clear modules and exercises, making it excellent for self-paced learning.
The Linux Command Line
A comprehensive and highly-regarded book for learning the Linux command line. The author makes the command line accessible to beginners while covering advanced topics. A free online version is available.