All Unix, Linux and other Unix-like operating systems are families of computer operating
systems derived from the original Unix System from Bell Telephone
Laboratories. Today, the largest Unix descendent directly certified as
"UNIX" is macOS by Apple. The original commercial Unix derivatives included
HP-UX, AIX and SunOS, to name a few. The diversity and perceived
incompatibility between various Unix systems led to the creation of
interoperability standards including the Portable Operating System Interface
Unix is the original and most powerful and popular multi-user and
multi-tasking Operating System. The basic concepts of Unix were originated
in the Multics project of 1969. The Multics system was intended as a
time-sharing system that would allow multiple users to simultaneously access
a mainframe computer. Ken Thompson, Dennis Ritchie, and others developed the
basic building blocks of Unix including a hierarchical file system and a
command line interpreter for the PDP-7. Multiple generations of Unix systems
were developed for myriad computers.
As mentioned, historical perceived incompatibility between the various early
Unix systems led to the creation of POSIX and the Single Unix Specification.
Historically, the rigid "standardization" approach led to the creation of
various open source approaches to Unix including the Free Software
Foundation (FSF), GNU and Linux. Unix programs were originally created
around core design philosophies that included requirements like single
purpose, interoperable, and working with a simple standardized text
interface. Unix systems are built around a core kernel that manages the
system and the other processes. Kernel subsystems may include process
management, file management, memory management, network management and
Unix is a multi-user system where the resources can be shared by various
Unix provides multi-tasking. Users can execute many processes at
the same time (practically speaking).
Unix was the first computer operating system that was written in a
high-level language (C Language).
Unix provides a hierarchical file structure which facilitated fast data
Unix has built-in networking functions so that computers can easily exchange
Unix functionality can be extended through user programs built on a
standard programming interface.
UNIX certifies compliance with a full set of interoperability standard, managed and maintained by the Open Group, which includes, not only the kernel, but the entire operating system.
What is Linux?
Linux is a Unix-like operating system created by Linus Torvalds at the
University of Helsinki in 1991. The name Linux refers to
the Linux kernel, the software on a computer which permits applications and
users to access the devices on the computer to perform specific
functions. The development of Linux was a landmark example of global, free
and open source software collaboration. Many companies and similar numbers
of individuals have released their own version of Unix-like operating
systems based on the Linux Kernel.
Similar to Unix kernels, the Linux kernel relays instructions from an
application from the computer's processor and sends the results back to the
Broader in scope than commercial Unix products, Linux has been installed on a variety of platforms including mobile phones, tablets, video game consoles, NAS storage arrays, routers and small embedded controllers.
Currently the world's largest and most powerful data centers and scientific
research centers use some "flavor" of Linux.
The development of Linux is a stellar example of the power of free and open
source software development and global human collaboration.
A Linux "distribution" is a release of a Unix-like operating system based on
the specifications of the Linux kernel.
Linux, like Unix, is a multi-user
system where the resources can be shared by various system users.
Linux, like Unix, provides
multi-tasking. Users can execute many processes at the same time
Linux, like Unix, was written in C.
Linux, like Unix, provides a
hierarchical file structure which facilitated fast data access.
Linux, like Unix, has built-in
networking functions so that computers can easily exchange information.
Linux, unlike UNIX, specifies only the kernel but
not the entire operating system.
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An Interest Fact about the History of Unix and Linux
vi is a "command-line" screen-oriented text editor originally created
for the Unix operating system by Bill Joy in 1976. Bill wrote vi as
the visual mode for a line editor called ex that Bill had written with
Chuck Haley. Many of today's implements of vi are written "from
scratch" as mostly compatible implementations of the original vi. Some
current implementations of vi trace their source code ancestry to Bill
Joy's original vi code. ex 1.1 was released as part of the first
Berkeley Software Distribution (BSD) Unix release in March 1978. In
version 2.0 of ex was released as part of Second BSD in May 1979 and
the editor was installed under the name "vi".
The name "vi" comes from the shortest unambiguous abbreviation for the
ex command "visual" which switches the ex line editor to visual mode.
A number of commercial software variations of vi are distributed with
proprietary implementations of Unix. vi was made freely available with
OpenSolaris and today (as it was decades ago) vi is considered a core and essential part of all Unix and Linux systems. For example, when someone remotely
logs into a server across the network, they generally will edit (and
often view) files remotely using vi.
Over the many years of Unix history vi has became the de facto
standard Unix editor (more popular than EMACS). The Single UNIX
Specification specifies vi and that means that every conforming Unix
system must support vi. vi is still widely used in Unix and Linux
operating systems. Learning and using vi is considered an essential
part of the Unix and Linux experience. We recommend all Unix and Linux
users learn, as a bare minimum, the basics of the vi editor.
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