How to use the command modprobe (with examples)

The ‘modprobe’ command is used to add or remove modules from the Linux kernel. This command is commonly used to manage kernel modules, which are pieces of code that can be dynamically loaded into or unloaded from the kernel without the need to restart the system. The ‘modprobe’ command provides several options to load, remove, and manage kernel modules efficiently.

Use case 1: Pretend to load a module into the kernel, but don’t actually do it

Code:

sudo modprobe --dry-run module_name

Motivation: There may be situations where you want to check if a particular module can be loaded into the kernel without actually loading it. This can be useful for testing purposes or to verify if the module is compatible with the current kernel configuration.

Explanation:

• sudo: Executes the ‘modprobe’ command with root privileges.
• --dry-run: Instructs the ‘modprobe’ command to simulate loading the module without actually doing it.
• module_name: Specifies the name of the module to be simulated.

Example output:

insmod /path/to/module_name.ko

This output demonstrates that the module could be loaded into the kernel. However, since ‘–dry-run’ was used, the operation was only simulated and not actually performed.

Use case 2: Load a module into the kernel

Code:

sudo modprobe module_name

Motivation: Loading modules into the kernel is necessary to provide additional functionality to the operating system. This may include device drivers or kernel extensions that enable hardware support or enhance the capabilities of the system. Using the ‘modprobe’ command allows users to easily load required modules into the kernel.

Explanation:

• sudo: Executes the ‘modprobe’ command with root privileges.
• module_name: Specifies the name of the module to be loaded into the kernel.

Example output: No output is displayed if the module is loaded successfully. If there is an error, relevant error messages will be shown.

Use case 3: Remove a module from the kernel

Code:

sudo modprobe --remove module_name

Motivation: Removing unnecessary or problematic modules from the kernel can help improve system performance or resolve compatibility issues. The ‘modprobe’ command with the ‘–remove’ option allows you to easily unload a module without having to restart the system.

Explanation:

• sudo: Executes the ‘modprobe’ command with root privileges.
• --remove: Instructs the ‘modprobe’ command to remove the specified module from the kernel.
• module_name: Specifies the name of the module to be removed.

Example output: No output is displayed if the module is successfully removed. If there is an error, relevant error messages will be shown.

Use case 4: Remove a module and those that depend on it from the kernel

Code:

sudo modprobe --remove-dependencies module_name

Motivation: When removing a module that has dependencies on other modules, you may want to automatically remove those dependent modules as well. This can help avoid leaving unused or conflicting modules in the kernel, leading to a cleaner and more efficient system configuration.

Explanation:

• sudo: Executes the ‘modprobe’ command with root privileges.
• --remove-dependencies: Instructs the ‘modprobe’ command to remove the specified module and its dependent modules from the kernel.
• module_name: Specifies the name of the module to be removed along with its dependencies.

Example output: No output is displayed if the module and its dependencies are successfully removed. If there is an error, relevant error messages will be shown.

Use case 5: Show a kernel module’s dependencies

Code:

sudo modprobe --show-depends module_name

Motivation: Understanding a kernel module’s dependencies is helpful when troubleshooting issues or analyzing system configurations. With the ‘modprobe’ command, you can easily list the dependencies of a specific module, which can provide insight into the module’s requirements and interaction with other modules.

Explanation:

• sudo: Executes the ‘modprobe’ command with root privileges.
• --show-depends: Instructs the ‘modprobe’ command to display the dependencies of the specified module.
• module_name: Specifies the name of the module to show dependencies for.

Example output:

insmod /path/to/dependency1.ko
insmod /path/to/dependency2.ko

This output displays the list of dependencies for the specified module. It shows the ‘insmod’ commands that would be executed to load the dependencies into the kernel.