5.1Hardware Fundamentals and Configuration

On Linux most device drivers ship as kernel modules, loaded into the kernel only when needed. When a USB device is not recognized or a NIC driver must be swapped, module operations and info commands are your hands and feet.

5.1.1Managing kernel modules

• lsmod lists loaded modules (lsmod | grep e1000 is the idiom).
• modprobe loads/unloads a module with its dependencies (modprobe e1000e / modprobe -r e1000e)—first choice in practice and on the exam.
• insmod/rmmod load/unload a single module (no dependency handling; takes a file path)—the low-level workers beneath modprobe.

5.1.2Storage devices and hardware information

• Mass storage: HDD (magnetic, cheap and large, moving parts) / SSD (flash, fast, shock-resistant, limited write cycles) / optical (DVDs—distribution/archival).
• Inspect with lspci (PCI devices—NICs, GPUs) and lsusb (USB devices).
• Windows into the kernel: /proc/ (process/kernel state; /proc/cpuinfo, /proc/meminfo), /sys/ (sysfs—the device tree), /dev/ (device files like /dev/sda).
• udev detects hot-plug events and creates/names device files in /dev/ dynamically (rules can pin names). D-Bus is the IPC that notifies desktops and services of events.