r.spread(1grass) on Linux
The text 902104429cf4, as Debian 11 (Bullseye) shipped it.
Simulates elliptically anisotropic spread. Generates a raster map of the cumulative time of spread, given raster maps containing the rates of spread (ROS), the ROS directions and the spread origins. It optionally produces raster maps to contain backlink UTM coordinates for tracing spread paths. Usable for fire spread simulations.