A Unix-like OS is an operating system based on Unix.
The number of process states in Unix systems is 9.
List of Unix-like OS
Unix-like OS families:
- Unix System V
- Xenix
- BSD
- Coherent
- Minix
- Linux OS
- Darwin
Unix System V
Unix System V was developed by AT&T.
Xenix
Xenix was a Unix-like OS licensed as UNIX by AT&T.
It was developed by Microsoft in the early 1980s.
It was oriented towards the business market, unlike Microsoft’s not-Unix-like MS-DOS that was oriented towards the mass market.
It was sold to Santa Cruz Operation (SCO) in the late 1980s, but it disappeared after the success of Linux OS.
Venix
Venix was a clone of Version 7 UNIX (V7) to the PDP-11 and later x86 PCs.
It was developed by VentureCom. It was released in the early 1980s.
It was targeted at academic and industrial use.
BSD
BSD is a family of operating system. Its main derivatives are FreeBSD, OpenBSD, NetBSD and DragonflyBSD.
Coherent
Coherent was a UNIX-like OS for x86 PCs.
It was released in 1983. It was developed by the American company Mark Williams Company.
It is FOSS under a BSD-3-clause license since 2015, but it was proprietary during its lifecycle.
Minix
Minix was an Unix-like OS, unlicensed by UNIX but fully POSIX compliant.
It was originally developed by Andrew Tannenbaum.
It was released in 1987.
It was source-viewable. The frustration of being legally unable to modify its code led Linus Torvalds to create Linux OS as a FOSS Unix-like OS.
Minix code repository at GitHub
Linux OS
Linux OS is a family of operating system based on the Linux kernel.
You can read this post about Linux OS.
Darwin
Darwin is an Unix-like OS.
macOS X, later rebranded as macOS (though it should not be confused with the original macOS), is based on Darwin.
It is developed by American company Apple.
Unix-like OS Characteristics
The most popular memory management in Unix-like OS is the combination of paging on demand and page segments, both with fixed-size pages.
Unix-like system use a disk partition for swapping.
Unix-like system use virtual memory.
Unix-like OS Standards
Initiatives to standardize Unix-like OS:
- SVID
- POSIX
- Single UNIX Specification
SVID
System V Interface Definition (SVID) is a standard that describes the AT&T UNIX System V behavior.
It belonged to AT&T, so the standard was vendor-dependent.
It was one of the first attempts to standardize Unix-like systems, but it was replaced in the 1990s by POSIX and SUS.
POSIX
POSIX is a standard maintained by IEEE Computer Society.
It avoids using the UNIX trademark in the name, as the trademark is not owned by IEEE.
The development of the POSIX standard takes place in the Austin Group, which is a joint working group of IEEE, ISO/IEC JTC 1/SC 22/WG 15 and The Open Group.
SUS
Single UNIX Specification (SUS) is a certification that holds the UNIX trademark.
POSIX forms the core of SUS.
The core specifications of the SUS known as Base Specifications are developed and maintained by the Austin Group.
History
Bibliography:
- SALUS, Peter H. “Quarter century of UNIX”.
- KERNINGHAM, Brian . “UNIX: a history and a memoir”.