Unix-like
A Unix-like (sometimes referred to as UN*X or *nix)
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
Other parties frequently treat "Unix" as a
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]
History
This section needs additional citations for verification. (April 2010) |
"Unix-like" systems started to appear in the late 1970s and early 1980s. Many
When AT&T allowed relatively inexpensive commercial binary sublicensing of UNIX in 1979, a variety of proprietary systems were developed based on it, including AIX, HP-UX, IRIX, SunOS, Tru64, Ultrix, and Xenix. These largely displaced the proprietary clones. Growing incompatibility among these systems led to the creation of interoperability standards, including POSIX and the Single UNIX Specification.
Various free, low-cost, and unrestricted substitutes for UNIX emerged in the 1980s and 1990s, including 4.4BSD, Linux, and Minix. Some of these have in turn been the basis for commercial "Unix-like" systems, such as BSD/OS and macOS. Several versions of (Mac) OS X/macOS running on Intel-based Mac computers have been certified under the Single UNIX Specification.[5][6][7][8][9][10][11] The BSD variants are descendants of UNIX developed by the University of California at Berkeley, with UNIX source code from Bell Labs. However, the BSD code base has evolved since then, replacing all the AT&T code. Since the BSD variants are not certified as compliant with the Single UNIX Specification, they are referred to as "UNIX-like" rather than "UNIX".
Categories
Dennis Ritchie, one of the original creators of Unix, expressed his opinion that Unix-like systems such as Linux are de facto Unix systems.[12] Eric S. Raymond and Rob Landley have suggested that there are three kinds of Unix-like systems:[13]
Genetic UNIX
Those systems with a historical connection to the AT&T codebase. Most commercial UNIX systems fall into this category. So do the BSD systems, which are descendants of work done at the University of California, Berkeley in the late 1970s and early 1980s. Some of these systems have no original AT&T code but can still trace their ancestry to AT&T designs.
Trademark or branded UNIX
These systems—largely commercial in nature—have been determined by the
Functional UNIX
Broadly, any Unix-like system that behaves in a manner roughly consistent with the UNIX specification, including having a "
Around 2001 Linux was given the opportunity to get a certification including free help from the POSIX chair Andrew Josey for the symbolic price of one dollar.[citation needed] There have been some activities to make Linux POSIX-compliant, with Josey having prepared a list of differences between the POSIX standard and the Linux Standard Base specification,[16] but in August 2005, this project was shut down because of missing interest at the LSB work group.[citation needed]
Compatibility layers
Some non-Unix-like operating systems provide a Unix-like compatibility layer, with varying degrees of Unix-like functionality.
- IBM z/OS's UNIX System Services is sufficiently complete as to be certified as trademark UNIX.
- MSYS2 each provide a GNU environment on top of the Microsoft Windows user API, sufficient for most common open sourcesoftware to be compiled and run.
- The MKS Toolkit and UWIN are comprehensive interoperability tools which allow the porting of Unix programs to Windows.
- Windows NT-type systems have a POSIX environmental subsystem.
- Subsystem for Unix-based Applications (previously Interix) provides Unix-like functionality as a Windows NT subsystem(discontinued).
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- Windows Subsystem for Linux version 2 (WSL2) provides a fully functional Linux environment running in a virtual machine.
Other means of Windows-Unix interoperability include:
- The above Windows packages can be used with various X servers for Windows
- Hummingbird Connectivityprovides several ways for Windows machines to connect to Unix and Linux machines, from terminal emulators to X clients and servers, and others
- The Windows Bourne Shell, some command-line tools, and a version of Perl
- Hamilton C shell is a version of csh written specifically for Windows.
See also
- List of Unix-like systems
- Berkeley Software Distribution
- Linux kernel and Linux distribution
- List of Linux distributions
- List of Unix commands
- List of operating systems
- Free Software Foundation and GNU Project
References
- ^ "Legal: Trademark Guidelines". The Open Group. Archived from the original on October 2, 2013. Retrieved November 4, 2013.
- The Jargon File. Retrieved January 22, 2009.
- ^ Gray v. Novell, X/Open Company, The SCO Group (11th Cir. January 7, 2011), Text.
- ^ "More Wayne Gray. No! Again? Still?! Yes. He Wants to Reopen Discovery in the USPTO Dispute". Groklaw. April 22, 2011. Archived from the original on June 18, 2022. Retrieved September 26, 2022.
- ^ "Mac OS X Version 10.5 on Intel-based Macintosh computers". The Open Group. Retrieved December 4, 2014.
- ^ "Mac OS X Version 10.6 on Intel-based Macintosh computers". The Open Group. Retrieved December 4, 2014.
- ^ "Mac OS X Version 10.8 on Intel-based Macintosh computers". The Open Group. Retrieved December 4, 2014.
- ^ "OS X Version 10.9 on Intel-based Macintosh computers". The Open Group. Retrieved December 4, 2014.
- ^ "OS X version 10.10 Yosemite on Intel-based Mac computers". The Open Group. Retrieved October 23, 2015.
- ^ "OS X version 10.11 El Capitan on Intel-based Mac computers". The Open Group. Retrieved October 23, 2015.
- ^ "macOS version 10.12 Sierra on Intel-based Mac computers". The Open Group. Retrieved October 13, 2016.
- ^ Interview with Dennis M. Ritchie Manuel Benet, LinuxFocus, July 1999
- ^ The meaning of 'Unix' Eric Raymond and Rob Landley, OSI Position Paper on the SCO-vs.-IBM Complaint
- ^ "Introduction to UNIX – Part 1: Basic Concepts". Archived from the original on April 5, 2018. Retrieved April 4, 2014.
- ^ "The Open Brand Fee Schedule". The Open Group. November 6, 2003. Retrieved July 22, 2022.
- ^ Andrew Josey (August 20, 2005). "Conflicts between ISO/IEC 9945 (POSIX) and the Linux Standard Base". The Open Group. Retrieved July 23, 2012.
- ^ "What is the Windows Subsystem for Linux?". Microsoft Docs. July 18, 2023.
External links
- Unix-like Definition, by The Linux Information Project (LINFO)
- UNIX history – a history time line graph of most UNIX and Unix-like systems by Éric Lévénez
- Grokline's UNIX Ownership History Project – a project to map out the technical history of UNIX and Unix-like systems at the Wayback Machine (archived June 22, 2004)