Sullivan's counting was based on symlinks to shared licence ï¬les, as well as regular expression matching, using standard Debian tools.
He started with Sarge, which was released in 2005, before version 3 of the GPL was released. He found a total of 15,195 packages of which 10,730, or 71 per cent, were licensed under the GPL family.
The next release Etch was in April 2007. There were 18,043 packages of which 13.872 or 77 per cent were under the GPL family. This was an increase of 6 per cent as far as the GPL family went with a rise of 18 per cent in the total number of packages in the distribution.
Lenny, the first Debian release after the GPLv3 was published, was released in February 2009; there were 21,994 packages and 19,218 were licensed under the GPL family. The number of packages showed an increase of 22 per cent while the GPL percentage rose by 10 per cent. Another statistic of note was 630 packages which were under the GPLv3 or LGPLv3 by name.
The last Debian release, Squeeze, which emerged in February 2011, had 28,126 packages of which 26,271, representing 93 per cent, were under the GPL family. And showing an increase of 400 per cent were GPLv3 and LGPLv3 packages which now totalled 3154.
Sullivan concluded that debate about use of the GPL family of licences was being framed.
He advised that one should pay close attention to counting methods. "When it comes to looking at a diï¬€erent, well-vetted frame of software - like what's in Debian GNU/Linux - GPL family use is very high."
He added: "Either way, don't overstate the popularity of licenses (sic) as proxy for organizational (sic) inï¬‚uence/success, whether for the FSF, Mozilla, Apache, or any others.
"Don't forget that the license (sic) and law are just tools to achieve the end. Instead of popularity, look at progress toward the goals, even if that progress has to be qualiï¬ed as tenuous. Don't forget that non-copyleft free software is still free software."