Best Books for Learning Linux Internals

Before I recommend anything, could you clarify what you mean by 'deep-dive'? Are you looking for kernel-level insight or just something covering a part of the broader GNU/Linux ecosystem? If it’s the kernel specifically, maybe start with simpler resources on other kernels first to build a foundation.

You should consider checking out "The Linux Programming Interface: A Linux and UNIX System Programming Handbook." It's widely recommended for understanding the Linux internals and the system programming aspects. It’s well-written and detailed! Here’s the link: https://www.amazon.com/Linux-Programming-Interface-System-Handbook/dp/1593272200?tag=guru990f-20&geniuslink=true

For a unique perspective, you might want to look at the heavily commented Linux Kernel source code available online. There's a PDF version that breaks down the code well. It could give you the internal insights you’re after! Here's the link: https://download.oldlinux.org/ECLK-5.0-WithCover.pdf

If you're looking for something focused on Linux internals, you should definitely check out the Debian Administrator Handbook if you're using a Debian or Ubuntu-based system. It’s more on the system’s aspects rather than just how-to guides. Also, there are specific documents like the official Ubuntu help resources which might offer insights depending on your needs.