History of linux

Mid 1960 - multics (a time sharing operating system) was getting developed by AT&T Bell but it was too large/complex.... finally AT&T pulled out from project.

In 1969-70,  Ken Thompson and Dennis Ritchie (both of AT&T Bell Laboratories) wrote Unix Operating system (on a much less scaled version).

Later they rewrote it in C, make it portable.

Unix philosophy was to use a large number of software tools, small programs that can be strung together through a command-line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality.

Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system.

Under Unix, the operating system consists of many utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space.

During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (BSD and System V) by commercial startups, including Sequent, HP-UX, Solaris, AIX, and Xenix. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 (SVR4), which was subsequently adopted by many commercial Unix vendors.

1983, none of the computer operating systerm was free.

1984, Richard M. Stallman (founder of Free Software Foundation) started developing the GNU operating system (a unix-like operating system)

The GNU Project has developed a comprehensive set of free software tools (cp, rm, vi, gcc) for use with BSD Operating system

By 1991, the GNU mid-level portions of the operating system were almost complete, and the upper level could be supplied by the X Window System, but the lower level (kernel, device drivers, system-level utilities and daemons) was still mostly lacking

GNU developed it's free operating system called 'GNU Hurd' which was an ambitious design, unexpectedly difficult to implement and has only been marginally usable.

At another hand, Tanenbaum started MINIX for educational purpose, and was first released in 1987, with its complete source code made available to universities for study in courses and research, however still licencsed.

1991, Linus Torvalds, who was working for MINIX, almost copy the concept from MINIX (which was more a micro kernel) and made a monolithic kernal called Linux and use GNU free utilities to proivde a 'free operating system'.

As 'hurd' was still not triggering, GNU also adopted Linux as kernal around 1992. Basically Linux was the 'kernal part' and the operating system was 'GNU/Linux' Operating system.