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Unix-like

A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. Although there are general philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like.

Some well-known examples of Unix-like operating systems include Linux and BSD. These systems are often used on servers as well as on personal computers and other devices. Many popular applications, such as the Apache web server and the Bash shell, are also designed to be used on Unix-like systems.


One of the key features of Unix-like systems is their ability to support multiple users and processes simultaneously. This allows users to run multiple programs at the same time and to share resources such as memory and disk space. This is in contrast to many older operating systems, which were designed to only support a single user or process at a time. Another important feature of Unix-like systems is their modularity. This means that the operating system is made up of many small, interchangeable components that can be added or removed as needed. This makes it easy to customize the operating system to suit the needs of different users or environments.

Definition[edit]

The Open Group owns the UNIX trademark and administers the Single UNIX Specification, with the "UNIX" name being used as a certification mark. They do not approve of the construction "Unix-like", and consider it a misuse of their trademark. Their guidelines require "UNIX" to be presented in uppercase or otherwise distinguished from the surrounding text, strongly encourage using it as a branding adjective for a generic word such as "system", and discourage its use in hyphenated phrases.[1]


Other parties frequently treat "Unix" as a genericized trademark. Some add a wildcard character to the name to make an abbreviation like "Un*x"[2] or "*nix", since Unix-like systems often have Unix-like names such as AIX, A/UX, HP-UX, IRIX, Linux, Minix, Ultrix, Xenix, and XNU. These patterns do not literally match many system names, but are still generally recognized to refer to any UNIX system, descendant, or work-alike, even those with completely dissimilar names such as Darwin/macOS, illumos/Solaris or FreeBSD.


In 2007, Wayne R. Gray sued to dispute the status of UNIX as a trademark, but lost his case, and lost again on appeal, with the court upholding the trademark and its ownership.[3][4]

IBM 's UNIX System Services is sufficiently complete as to be certified as trademark UNIX.

z/OS

MSYS, and MSYS2 each provide a GNU environment on top of the Microsoft Windows user API, sufficient for most common open source software to be compiled and run.

Cygwin

The and UWIN are comprehensive interoperability tools which allow the porting of Unix programs to Windows.

MKS Toolkit

Windows NT-type systems have a environmental subsystem.

POSIX

(previously Interix) provides Unix-like functionality as a Windows NT subsystem (discontinued).

Subsystem for Unix-based Applications

Windows Subsystem for Linux

[17]

employs the third-party musl libc library and native APIs ports, providing support on POSIX for Linux syscalls within the Linux kernel and LiteOS default kernels side of the system multi-kernel Kernel Abstract Layer subsystem for vendor and developers interoperability.

OpenHarmony

with HarmonyOS NEXT system has OpenHarmony user mode that contains musl libc library and native APIs ports, providing support with POSIX for Linux syscalls within the default kernels of the Linux kernel standard system and LiteOS small and lightweight system side of the system multi-kernel Kernel Abstract Layer subsystem for interoperability on legacy Unix-like functionalities.

HarmonyOS

Some non-Unix-like operating systems provide a Unix-like compatibility layer, with varying degrees of Unix-like functionality.


Other means of Windows-Unix interoperability include:

List of Unix-like systems

Berkeley Software Distribution

and Linux distribution

Linux kernel

List of Linux distributions

List of Unix commands

List of operating systems

and GNU Project

Free Software Foundation

by The Linux Information Project (LINFO)

Unix-like Definition

 – a history time line graph of most UNIX and Unix-like systems by Éric Lévénez

UNIX history

at the Wayback Machine (archived June 22, 2004)

Grokline's UNIX Ownership History Project – a project to map out the technical history of UNIX and Unix-like systems