lsmod

lsmod is a Linux command-line utility that reports information about currently loaded kernel modules. It derives its data from the /proc/modules pseudo-file and presents a concise snapshot of the module state for the running kernel. The tool itself does not modify module state; it is a read-only utility used for inspection and diagnostics.

The typical output of lsmod consists of one line per loaded module, with columns showing the module name, the size of the module in memory, and the number of other modules that use it (the “Used by” field). In many implementations, the Used by column may also list the names of dependent modules. A module with no dependents often shows 0 or an empty Used by entry. lsmod thus helps users understand module dependencies and diagnose why certain modules remain loaded.

lsmod is part of the util-linux package on most modern distributions; older systems may have used the module-init-tools or kmod packages. It is a non-privileged utility and reads information from /proc/modules, so it can be run by any user. When troubleshooting hardware or driver issues, lsmod is commonly used in combination with tools such as modprobe, insmod, and rmmod to load, insert, or remove modules, respectively.

Common usage patterns involve filtering the output to locate a specific module, for example by piping to grep (lsmod | grep name). Since lsmod only reports the current state, it is typically used alongside other commands to inspect module availability and dependencies during system diagnosis. See also: /proc/modules, modprobe, insmod, rmmod.