[thesuperbigfrog]

"The Linux Programming Interface" by Michael Kerrisk is one of the best technical resources I have found and used to understand Linux:

https://man7.org/tlpi/

Description from the book's website:

"The Linux Programming Interface (TLPI) describes system programming on Linux and UNIX.

TLPI is both a guide and reference book for system programming:

If you are new to system programming, you can read TLPI linearly as an introductory guide: each chapter builds on concepts presented in earlier chapters, with forward references kept to a minimum. Most chapters conclude with a set of exercises intended to consolidate the reader's understanding of the topics covered in the chapter.

If you are an experienced system programmer, TLPI provides a comprehensive reference that you can consult for details of nearly the entire Linux and UNIX (i.e., POSIX) system programming interface. To support this use, the book is thoroughly cross referenced and has an extensive index."