uml_mconsole(1) on Linux
The text c64a6bcacbd3, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch) shipped it. The page shows this text now.
attach to the management console of a user-mode Linux kernel