Unix

Unix is a family of operating systems that can handle many tasks at once and allow many users to work on the same computer. It began in 1969 at Bell Labs. It was made by Ken Thompson, Dennis Ritchie, and others. At first, it was used inside the Bell System, but later it was shared with other companies, which created many different versions.

Early Unix worked on computers like the PDP-11 and VAX. What made Unix special was that it could run on many types of computers. This was because it was mostly written in the C programming language. Unix is known for its simple tools, each doing one specific job. These tools can be combined to do more complex tasks.

Over time, many companies made their own versions of Unix. Some used one set of features, while others used a different set. Today, some Unix systems are still used, especially in certain areas. Many modern systems are based on Unix-like clones such as Linux and GNU.

Overview

Unix started as a simple tool for programmers to create and run software. Over time, it became popular in schools and among users who added their own tools and shared them with others.

Unix wasn’t always able to handle many tasks at once or work on different types of computers. But it later learned to do both. Unix systems are special because they use plain text to store information, have an organized way to store files, and let small programs work together through commands. This way of doing things is called the “Unix philosophy”.

By the 1980s, people saw Unix as a useful system for all kinds of computers. The Unix way of doing things helped shape the development of the Internet and changed computing to focus more on networks than single computers.

Both Unix and the C programming language were created by AT&T and shared with schools and governments. This allowed them to work on many different kinds of computers.

The Unix operating system includes many tools and libraries, plus a main program called the kernel. The kernel helps manage programs, handles files, and makes sure programs don’t interfere with each other when they need the same things. The kernel has special powers to keep everything running smoothly.

History

Main article: History of Unix

Unix began in the mid-1960s when three groups worked on an operating system called Multics. Some people at Bell Labs found Multics too big and complicated, so they decided to make something new and simpler.

Ken Thompson, Dennis Ritchie, and a few others started working on this new system without any official support or name at first. In 1970, they called it Unics as a fun twist on Multics. Later, it became known as Unix. The early versions of Unix ran on computers like the PDP-11 and were used on many machines from the 1970s onward. Over time, many companies made their own versions of Unix, and it became very popular for powerful computers and servers.

Standards

In the late 1980s, a group worked to create a common standard for operating systems, called POSIX. This standard was based on the main versions of Unix and was first published in 1988 by IEEE.

Later, in the early 1990s, another group called the Common Open Software Environment started a similar effort, which became the Single UNIX Specification managed by The Open Group. In 1998, these groups joined together in the Austin Group to create a unified standard.

In 1999, many Unix companies agreed to use the same format for program files, called the Executable and Linkable Format, so programs could work on different Unix systems. There is also a Filesystem Hierarchy Standard that helps organize files in a consistent way for Unix-like systems, mostly used in Linux.

Components

The Unix system has several parts that work together. It has a main part called the kernel. The kernel helps manage memory and programs.

There are also tools for making and managing programs, like editors and compilers.

Unix has many commands that users can type. These commands help users do things like copy files or search for text. There are help pages called "man" pages. They explain how to use each command. All these parts work together to make Unix easy to learn and use.

Impact

See also: Unix-like

The Unix system changed how computers worked in many ways. It became well-known because it was easy to use and cheap for schools. It could run on less expensive computers. Unix was first written in a special language called assembly, but it was later changed to C, a more common language for programming.

Unix made files simple. It treated all kinds of files the same way, like lists of numbers. This made it easier to organize and use files.

Unix also made it easy to add new commands and tools. Users could pick their own tools or make new ones without changing the main system. This helped many later systems learn from Unix.

Unix focused on using text for most things, which made it easier to connect different tools together. This helped Unix grow and work well on many different machines. Over time, many tools came from Unix ideas.

Free Unix and Unix-like variants

See also: Operating system § Unix and Unix-like operating systems

In 1983, Richard Stallman started a project to make a free version of Unix. In 1991, Linus Torvalds created a part called the Linux kernel, which helped make this idea real. Many people now use systems that include Linux, like Debian and Ubuntu.

There are also systems based on another version called BSD Unix, such as FreeBSD and OpenBSD. These systems share ideas with each other and with older Unix systems.

Because Unix was designed to be flexible, many modern systems use parts from it. Linux and BSD Unix are now used in many places, from home computers to phones and small devices.

ARPANET

Main article: ARPANET

In 1975, people at a university described how Unix could work well on a network called ARPANET. At the time, using Unix needed a special permission, which cost a lot for regular groups but was cheap for schools. Unix had many tools that made it useful for network work. This helped Unix become part of the early internet ideas.

Branding

See also: List of Unix systems

AT&T used to not let companies use the name Unix for their versions. For example, Microsoft called its version Xenix. In 1988, AT&T changed this rule. After that, companies could use the UNIX name if they followed certain rules.

Today, The Open Group owns the UNIX trademark. Only systems that follow The Open Group's rules can be called "UNIX." Other systems are called "Unix-like." Some systems that can use the UNIX name include AIX, HP-UX, macOS, and Solaris.

Sometimes people use symbols like Un*x or *NIX to talk about all systems similar to Unix. This comes from computer commands that use asterisks to stand for many things.

The Open Group wants people to use UNIX as a description, like saying "UNIX system." The original name was written as Unix, but UNIX is now common. It is not an acronym.

Different countries have different rules for trademarks, so Unix has been used for many products besides computer systems, like bookshelves and glue. People sometimes say "Unixes" or "Unices" when talking about many types of Unix systems.