What's changed: Initial version (topic 1.05, subtopics 1.05.1–1.05.3)
5.1Hardware Fundamentals and Configuration
Learn how Linux recognizes and controls hardware: kernel module operations (lsmod, modprobe, insmod, rmmod), storage differences (HDD, SSD, optical), hardware information (lsusb, lspci, /sys/, /proc/, /dev/), and the concepts of sysfs, udev, and D-Bus.
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 e1000is 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.
Standard pairings: load with dependencies = modprobe / single = insmod, PCI = lspci, USB = lsusb, dynamic /dev management = udev. Also frequent: unloading via modprobe -r (or rmmod), and /proc & /sys being virtual filesystems with no on-disk presence.
Trace "USB stick inserted → usable" and the pieces connect. The kernel detects insertion, auto-loads the right kernel module (usb-storage), and publishes device details in sysfs (/sys/). udev, watching sysfs, creates the device file (e.g., /dev/sdb) per its naming rules, while D-Bus notifies the desktop ("new device arrived"—why your file manager pops up). Troubleshoot in reverse: no device file → check physical recognition with lsusb/lspci → check the driver is loaded with lsmod → load manually with modprobe drivername if needed. insmod needs a file path (insmod /path/to/driver.ko) and resolves nothing, so preferring name-only modprobe matches both the exam and real practice.
| Goal | Command/place | Key point |
|---|---|---|
| List loaded modules | lsmod | Usually piped to grep |
| Load/unload with deps | modprobe / modprobe -r | Takes just a name |
| Inspect PCI / USB | lspci / lsusb | Confirms physical detection |
| Dynamic device files | udev (/dev/) | Watches sysfs, notifies via D-Bus |
Trap: "insmod takes a module name and loads dependencies" is wrong—name-based, dependency-aware loading is modprobe; insmod loads one file by path. And "/proc contents are stored on disk" is wrong—/proc and /sys are virtual filesystems generated in memory by the kernel.
5.1.3Section summary
- Modules: check with lsmod, modprobe (with deps), insmod/rmmod (single)
- Info via lspci/lsusb, /proc, /sys (sysfs), /dev; udev manages /dev dynamically, D-Bus notifies
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Quick check
(just a quick review)Q1. You want to load the e1000e NIC driver together with its dependencies. Which command?
Q2. You want to check whether a USB device attached to the server is recognized. Which command?
Q3. Plugging in a USB stick automatically creates a device file like /dev/sdb. Which mechanism does this?
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