"It's been about 15 years since the original version of the
Linux kernel was produced by Linus Torvalds, and over those 15
years, Linux has grown from a toy into a functional OS with some
potential. My congratulations to all involved.
"The maturation of Linux has been reasonably swift--due
essentially to the duplication through the direct copying or
reverse engineering of all manner of features/tools/utilities found
in the Unix environment. So although reasonably swift, still
probably encompassing several hundred thousand man of development,
the vast bulk of Linux development is a result of the million or so
of man years of development of the various versions of the Unix
operating system on which it has piggybacked..."
