Test Your Knowledge in Computers #817
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In CSS, E[foo="bar"] matches an E element whose "foo" attribute value is exactly equal to "bar".
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UNIX, Linux and the Key Differences
What is Unix?

All Unix and 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 preceived incompatibility between various Unix systems led to the creation of interoperability standards including the Portable Operating System Interface (POSIX).
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 others.
Key Features:
  1. Unix is a multi-user system where the resources can be shared by various system users.
  2. Unix provides multi-tasking. Users can execute many processes at the same time (practically speaking).
  3. Unix was the first computer operating system that was written in a high-level language (C Language).
  4. Unix provides a hierarchical file structure which facilitated fast data access.
  5. Unix has built-in networking functions so that computers can easily exchange information.
  6. Unix functionality can be extended through user programs built on a standard programming interface.
  7. 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 application.
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.
Key Features:
  1. Linux, like Unix, is a multi-user system where the resources can be shared by various system users.
  2. Linux, like Unix, provides multi-tasking. Users can execute many processes at the same time (practically speaking).
  3. Linux, like Unix, was written in C.
  4. Linux, like Unix, provides a hierarchical file structure which facilitated fast data access.
  5. Linux, like Unix, has built-in networking functions so that computers can easily exchange information.
  6. 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
UNIX and Linux

Unix (trademarked as the UNIX certification mark) is a very mature family of multitasking, multiuser computer operating systems that evolved from the original AT&T Unix. Unix development starting in the 1970s by legendary Bell Labs programmers Ken Thompson, Dennis Ritchie, and others. Unix was first targeted for the Bell System and AT&T licensed Unix to outside parties. In the 1970s time period, this lead to a variety of for-profit as well as not-for-profit Unix variants.
In the early days, this included the University of California, Berkeley (BSD), Microsoft (Xenix), IBM (AIX), and Sun Microsystems (Solaris). In the early 1990s, AT&T sold their Unix rights to Novell. In 1995 Novell sold their Unix business to the Santa Cruz Operation (SCO). The UNIX trademark was passed to The Open Group, a "neutral" industry consortium. The Open Group promoted the use of the UNIX trademark for certified operating systems that comply with the Single UNIX Specification (SUS). In 2014 Apple's macOS became the Unix version with the largest global install base and macOS remains the largest Unix-user base today.
Linux is a family of open source Unix-like operating systems based on the Linux kernel. The Linux kernel is an operating system kernel first released by Linus Torvalds on 17 September 1991. Linux distributions include the Linux kernel, system software and libraries. Popular free open source Linux distributions include Debian, Fedora, and Ubuntu. Commercial Linux distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise Server. Linux may be freely modified and redistributed. Anyone on the planet may create a Linux distribution for any purpose.
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