Three Linux distros gave the same results, all three from nonroot accounts and one also from root: Debian 8.8.0 (modern but no WiFi), Knoppix 7.2 (old but WiFi ok), & Porteus 1.1 (old but WiFi ok):
Terminal output (without quote marks): "Usage: lsmod"
No link to pastebin.com for these, since loaded-modules.txt on desktop was 0 KiB in every case (4 cases).
The root account is mysteriously inaccessible in Debian although the password works to authenticate me for a root-level function from a nonroot account. Knoppix appears to run (when live) in one account only; logging out brings me right back to the Knoppix desktop without a visible chance to log into any account. Porteus live gave the same result in root and in the nonroot account, and WiFi worked in Porteus in root and nonroot.
Someone else suggested different CLI input, and I've posted that output to pastebin.com (preserving brackets, leading whitespace (perhaps not as tabs), and blank lines as in original):
Does that clarify things? Thank you very kindly.