Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or certified to any version of the Single UNIX Specification. The term encompasses a wide range of operating systems sharing characteristics with the original Unix system developed at Bell Labs.

Generally, a Unix-like system exhibits traits such as a hierarchical file system, the concept of treating all resources as files, a command-line interface (CLI), utilities for text manipulation and process control, and the use of shell scripting.

The category of Unix-like systems includes several major branches:

• BSD (Berkeley Software Distribution) derivatives: This branch includes operating systems like FreeBSD, NetBSD, OpenBSD, and macOS. These systems trace their lineage back to Unix code developed at the University of California, Berkeley.

• System V derivatives: This branch includes systems such as Solaris, HP-UX, and AIX. These are based on the AT&T System V release of Unix.

• Linux distributions: While Linux itself is a kernel and not a complete operating system, the various Linux distributions (e.g., Debian, Ubuntu, Fedora, SUSE) that incorporate the Linux kernel along with other system software are considered Unix-like. These distributions typically adhere to the POSIX standard.

• Minix-inspired systems: MINIX, a minimalist Unix-like operating system intended for educational purposes, also inspired the creation of other systems.

The term "Unix-like" is used to distinguish these systems from proprietary Unix implementations that are certified to meet the Single UNIX Specification. While Unix-like systems may implement many of the same features and functionalities as certified Unix systems, they may not have undergone the certification process or may contain differing implementations. The term highlights functional similarity rather than strict compliance.