Linux turned 25

Time is running very quickly, and the Linux operating system exists over a quarter of the century. It would be better to say that the core of this operating system turned 25 years old. August 25, 1991, five months after the work on this project was started, 21-year-old Linus Torvalds (then a student) announced that the prototype of a completely new operating system -Linux was created.

September 17, 1991, the first public release of the Linux core. Core version at the time was - 0.0.1. Even then, the number of lines of the core code was approximately 10 thousand. Its size was only 62 KB compressed. Now, the core has many times more lines of code as much as 19 millions. If the OS development carried out commercial organisation forces, the cost of such a project would have amounted to about one billion US dollars, or even more.

Linus Torvalds decided to create the core after work with MINIX operating system. It did not work for the limited student license. As the result, Torvalds was accused of plagiarism. He was accused of copying the code from subsystems MINIX. But the experts were able to refute the accusation. The author of MINIX, Andrew Tanenbaum has compared its OS and the Linux code, and came to the conclusion that there are only a few inconsequential matches in the code, which can be ignored. These matches were due to POSIX and ANSI C requirements.

Since its first release, the core has undergone many transformations. That visual statistics:

• 0.0.1 - September 1991 10 thousand lines of code;
• 1.0.0 - March 1994, 176 thousand lines of code;
• 1.2.0 - March 1995, 311 thousand lines of code;
• 2.0.0 - June 1996, 778 thousand lines of code;
• 2.2.0 - January 1999 1.8 million lines of code;
• 2.4.0 - January 2001 3.4 million lines of code;
• 2.6.0 - December 2003, 5.9 million lines of code;
• 2.6.28 - December 2008, 10.2 million lines of code;
• 2.6.35 - August 2010, 13.4 million lines of code;
• 3.0 - August 2011, 14.6 million lines of code;
• 3.5 - July 2012 15.5 million lines of code;
• 3.10 - July 2013 15.8 million lines of code;
• 3.16 - August 2014, 17.5 million lines of code;
• 4.1 - June 2015, 19.5 million lines of code;
• 4.7 - July 2016 21.7 million lines of code.

The core strength has been developing by a third-party developers. On Linux Foundation reports, since 2005 - 13,500 professionals participated in the development of the system. The average speed of work on the system was - 7.8 patches per hour. The development system was attended not only by independent developers ​but also many representatives of major technology corporations took part in it. Additionaly​, ​contribution of such companies as Intel, Red Hat, Linaro, Samsung, SUSE, IBM, Renesas, Google, AMD, Taxas Instuments and ARM can be mentioned.