GNU/Linux Would Cost Over $1 Billion to Rebuild, Study Finds
More Than a Gigabuck: Estimating GNU/Linux's Size (2001)
David A. Wheeler's 2001 analysis of Red Hat Linux 7.1 reveals that the distribution contains over 30 million physical source lines of code, requiring an estimated 8,000 person-years and over $1 billion to develop conventionally. This represents a 60% increase over Red Hat Linux 6.2 from a year earlier. The largest components include the Linux kernel, Mozilla, and X Windows, with C dominating at 71% of code. The GNU GPL is the most prevalent license, covering 63% of the code.
In all ways, the copylefting licenses (GPL and LGPL) are the dominant licenses in this Linux distribution.