lsmod Command in Linux: List and Inspect Kernel Modules

The lsmod command in Linux lists all currently loaded kernel modules. It reads /proc/modules — a virtual file maintained by the kernel — and formats the output into three labeled columns.

lsmod takes no options or arguments.

How to Use the lsmod Command in Linux

Run it without any flags:

bashlsmod

The output looks like this:

Module                  Size  Used bykvm_intel             278528  0kvm                   651264  1 kvm_intelirqbypass              16384  1 kvmahci                   40960  1libahci                32768  1 ahci

Each row has three columns:

• Module — the name of the loaded module
• Size — memory used by the module, in bytes
• Used by — the number of instances currently using it, followed by a comma-separated list of modules that depend on it

A “Used by” count of 0 means the module is loaded but not actively in use and has no dependents. It is a candidate for removal.

Reading Dependencies and Knowing What Can Be Safely Removed

The “Used by” column is the key field for safe module management.

In the output above, kvm_intel depends on kvm — its name appears in kvm‘s dependency list. To remove kvm, you must first run modprobe -r kvm_intel. Attempting to remove kvm while kvm_intel is loaded fails with a “module is in use” error.

Modules reach the system in three ways: automatically by udev when hardware is detected, manually with modprobe, or at boot via /etc/modules or /etc/modules-load.d/*.conf. Modules compiled directly into the kernel at build time are called built-in modules and do not appear in lsmod output at all.

For scripts that need raw module data, read the source file directly:

bashcat /proc/modules

Filter Output and Get Module Details with modinfo

To check whether a specific module is loaded:

bashlsmod | grep kvm

To list modules whose “Used by” count is 0:

bashlsmod | awk '$3 == 0'

$3 targets the third column in each row. A zero count means the module can be unloaded without breaking anything that depends on it.

To get detailed information about a specific module before acting on it:

bashmodinfo kvm

The output includes the file path, license, author, description, and configurable parameters. The file path shows the kernel version the module belongs to. Modules live in /lib/modules/<kernel_version>/ and are version-specific — a module built for one kernel will not load on another.

To unload a module and its dependencies:

bashsudo modprobe -r kvm_intel

Only run modprobe -r after confirming the “Used by” count is 0 and no service or device depends on the module.

Start with lsmod to see what is loaded, use grep to look up a specific module, awk '$3 == 0' to find removal candidates, and modinfo to review details before making changes. Leave a comment below if you run into any issues.