Wikipedia
lsmod is a command on Linux systems which prints the contents of the [[procfs|/proc/modules]] file. It shows which loadable kernel modules are currently loaded.
Abridged example output:
# lsmod
Module Size Used by
af_packet 27392 2
8139too 30592 0
snd_cs46xx 96872 3
snd_pcm_oss 55808 1
snd_mixer_oss 21760 2 snd_pcm_oss
ip6table_filter 7424 1
ip6_tables 19728 1 ip6table_filter
ipv6 290404 22
xfs 568384 4
sis900 18052 5
libata 169920 1 pata_sis
scsi_mod 158316 3 usb_storage,sd_mod,libata
usbcore 155312 6 ohci_hcd, usb_storage, usbhid
"Module" denotes the name of the module. "Size" denotes the size of the module (not memory used). "Used by" denotes each module's use count and a list of referring modules. The "Used by" list is sometimes incomplete. If the module controls its own unloading via a can_unload routine then the use count displayed by lsmod is always -1, irrespective of the real use count.