A Helsinki student's hobby kernel now runs every top supercomputer
In 1991 Linus Torvalds, a University of Helsinki student frustrated that the teaching system Minix was restricted to education, began writing his own operating system kernel. He released it on 17 September 1991. Torvalds later said that if a free GNU kernel or 386BSD had existed then, he probably would never have bothered.
The backdrop was Unix, created at AT&T's Bell Labs in 1969 by Ken Thompson, Dennis Ritchie and colleagues and rewritten in C in 1973, which made it easy to move between machines. A 1956 antitrust ruling kept AT&T out of the computer business, so it handed the source code to anyone who asked, and Unix spread through universities. After AT&T's 1984 breakup freed it to sell Unix commercially, users lost the right to modify it. Richard Stallman's GNU Project, begun in 1983, set out to build a free replacement and by the early 1990s had compilers, editors and shells, but its own kernel was stalled.
Torvalds met Unix in a 1990 course whose textbook, by Andrew Tanenbaum, came with Minix. Unable to get the POSIX standards documents, he worked out system calls from the university's SunOS manuals and Tanenbaum's book. He first developed on Minix, then swapped in GNU tools and moved his project to the GPL licence, which requires anyone distributing modified code to share their source. Because Linux contained no Unix code, it sidestepped legal trouble from AT&T.
The result conquered almost everything except the desktop, where it held about 4 percent in 2024. Linux runs over 96 percent of the top million web servers and, since November 2017, all 500 of the world's fastest supercomputers. Counting Android, it has the largest installed base of any general-purpose operating system, and it sits inside smart TVs, cars and even the Ingenuity Mars helicopter. Thousands of distributions exist, such as Debian and Ubuntu.
The effort behind it is huge. A 2001 study found Red Hat Linux 7.1 held 30 million lines of code, representing roughly eight thousand person-years of work; Debian 4.0 in 2007 came to nearly 283 million lines, worth an estimated 10.4 billion dollars.
Source: Linux
