06-B.5: Kernel Module Management - lsmod/modinfo Command

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The lsmod Command

The lsmod command is used to display the status of modules in the Linux kernel. It results in a list of loaded modules. lsmod is a trivial program which nicely formats the contents of the/proc/modules, showing what kernel modules are currently loaded.

This video covers the Linux kernel module commands. While the commands are not overly complex, there are some good examples of how to use them in the video.

Syntax:

lsmod

Example:

pbmac@pbmac-server $ lsmod
Module                  Size  Used by
hid_logitech_hidpp     36864  0
hid_logitech_dj        20480  0
vmw_vsock_vmci_transport    32768  0
vsock                  36864  1 vmw_vsock_vmci_transport
vmw_vmci               69632  1 vmw_vsock_vmci_transport

Output Format: There are three columns in output.

First column is used for ‘Name‘ of the module file.
Second column is used for ‘size‘ of the module in Bytes.
The third column in output is for ‘used by.‘ It is basically used to display the number of instances of the module which are used.

The modinfo Command

The modinfo command is used to display the information about a Linux Kernel module. This command extracts the information from the Linux kernel modules given on the command line. If the module name is not a file name, then the /lib/modules/$(uname -r)directory is searched by default. modinfo can understand modules from any of the Linux Kernel architecture.

Syntax:

modinfo [ OPTION ] [modulename|filename...]

modinfo Command Options

Options	Options Meaning
-F, --field	Only print this field value, one per line. This is most useful for scripts. Field names are case-insensitive. Common fields (which may not be in every module) include author, description, license, parm, depends, and alias. There are often multiple parm, alias and depends fields. The special field filename lists the filename of the module.
-b basedir, --basedir basedir	Root directory for modules, / by default.
-k kernel	Provide information about a kernel other than the running one.
-l, --files-with-matches	Suppress normal output; instead print the name of each input file from which output would normally have been printed. The scanning will stop on the first match.
-o, --only-matching	Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
-v, --invert-match	Invert the sense of matching, to select non-matching lines.
-f FILE, --file=FILE	Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the -e (--regexp) option, search for all patterns given. The empty file contains zero patterns, and therefore matches nothing.

Taking the name returned in the output of lsmod, it is possible to find out more about a particular module as seen below.

pbmac@pbmac-server $ lsmod
Module                  Size  Used by
...
vboxdrv               483328  2 vboxnetadp,vboxnetflt
pbmac@pbmac-server $ modinfo vboxdrv
filename:       /lib/modules/4.15.0-91-generic/misc/vboxdrv.ko
version:        6.1.6 r137129 (0x002d0001)
license:        GPL
description:    Oracle VM VirtualBox Support Driver
author:         Oracle Corporation
srcversion:     1B117C52DF5B4D7EFB983ED
depends:        
retpoline:      Y
name:           vboxdrv
vermagic:       4.15.0-91-generic SMP mod_unload 
parm:           force_async_tsc:force the asynchronous TSC mode (int)

Adapted from:
"lsmod command in Linux with Examples" by Narendramnitcse, Geeks for Geeks is licensed under CC BY-SA 4.0
"modinfo command in Linux with Examples" by Rahulkumarmandal, Geeks for Geeks is licensed under CC BY-SA 4.0