The Xunil Pages: The definition of open depends on your platform by Evan Leibovitch

“In so many ways, Linux has taken all the good facets of Unix
and dispensed with the cruft.”

“Over time, the Unix definition of “open” came to refer to
nothing more than a technology whose owner would be prepared to
license it to third parties.”

“The Linux definition of “open” is far different… it literally
requires its code be made available in source form and freely