CompTIA Linux+ Certification XK0-006 Flashcards - Section 4: Device Management

kernel modules

Software components that extend the functionality of the Linux OS.

insmod command

Manually inserts a kernel module without resolving dependencies.

syntax for insmod

insmod /lib/modules/$(uname -r)/extra/custom_module.ko

$(uname -r) with insmod

It dynamically retrieves the current kernel version for compatibility.

modprobe command

Loads kernel modules and their dependencies automatically.

modprobe options

-a (load multiple), -r (remove), -f (force), -n (dry run), -v (verbose), -s (log output)

modprobe -r wifi_driver

Removes the wifi driver module safely.

rmmod command

Removes a kernel module but does not check dependencies.

when to use rmmod

In emergencies or for manual unloading, with caution.

depmod command

Analyzes module dependencies and helps modprobe load them correctly.

lsmod

Lists all loaded kernel modules, their sizes, and dependencies.

why use lsmod

To identify unnecessary, conflicting, or unauthorized kernel modules.

modinfo

Provides detailed information about a kernel module (author, version, etc.).

dmidecode command

Deep hardware info from the DMI table (BIOS, motherboard, CPU, memory).

lscpu command

Displays CPU architecture, cores, cache sizes, and NUMA configuration.

lscpu -e

Extended CPU info including NUMA node, socket, core, and cache details.

NUMA

Non-Uniform Memory Access, a system architecture that optimizes memory access in multi-CPU setups.

lsmem command

Displays how memory is structured, including block ranges and removable status.

RANGE in lsmem

Starting and ending memory block addresses.

STATE in lsmem

Whether a memory block is online or offline.

lspci

Lists all PCI devices and their hierarchy.

lspci -tv

Structured tree view of PCI devices with device addresses and descriptions.

lsusb

Connected USB devices with their bus, device number, and IDs.

lshw command

Provides a comprehensive breakdown of hardware components.

lshw -short

A summarized list of devices with hardware path, type, and name.

dmesg command

Displays system messages and hardware logs (useful for boot and error diagnostics).

useful dmesg options

-l (filter), -H (human-readable), -c (clear), -f (filter facility), -L (color output), -e (timestamps)

lm_sensors

Monitors hardware temperature, voltage, and fan speed.

view sensor data in real time

Use the command: watch sensors

ipmitool

Provides remote diagnostics and power management for server hardware.

syntax of ipmitool

ipmitool [options] [command-specific arguments]

initrd

A temporary filesystem used during boot to load essential drivers and tools.

mkinitrd

Manually creates an initrd image for early boot drivers.

syntax for mkinitrd

mkinitrd [options]

common mkinitrd options

--preload, --with=module, -f (force), --nocompress

dracut

Modern tool to create initramfs images with better dependency management.

syntax for dracut

dracut [options]

common options for dracut

--force, --add-drivers, --omit-drivers, --no-compress

initramfs

A temporary root filesystem created by dracut during the Linux boot process.

importance of initrd/initramfs

It ensures required drivers are loaded before mounting the real root filesystem.

embedded systems

Specialized computers designed for specific tasks with high reliability and low power use.

OS for embedded systems

Lightweight Linux distros or Real-Time Operating Systems (RTOS).

RTOS

Real-Time Operating System designed to process tasks with strict timing constraints.

GPU acceleration

Used for AI, video editing, simulations, crypto mining, and other compute-heavy tasks.

why GPUs are good for complex tasks

They support parallel processing of large datasets.

nvtop

Monitors GPU usage, temperature, and memory in real time.