Unix and Linux System Administration Handbook

I'm going to cast a vote for 'Unix & Linux System Administration Handbook' - it's been around a long time and is currently on edition 5. It's the book that made me fall in love with system administration. It's an extensive and well-rounded look at various fundamental system administration topics with examples included from multiple different *nix distributions (topics like work management, logging, networking, security, the kernel, systemd, permissions, etc.). If you're at all interested in Linux, this is a great book to have on your shelf. https://admin.com/