An operating system is said to be Unix-based or Unix-like if it’s designed to function and behave similar to the Unix operating system. Examples of proprietary Unix-like operating systems include AIX, HP-UX, Solaris, and Tru64. Examples of open-source Unix-like operating systems are those based on the Linux kernel and BSD derivatives, such as FreeBSD and OpenBSD.

Characteristics

All Unix-like operating systems support multiple users, strict segregation between kernel and user processes, preemptive multitasking, and a hierarchical file system. They often share the characteristic known as “everything is a file.” Almost every system device and resource is abstracted as a stream of bytes that can be read and written like a regular file.

The GNU toolchain is a collection of compilers, libraries, debuggers, and core utilities modeled on Unix. It’s been ported to many Unix-like operating systems, and is used by default on GNU/Linux systems.

The Single Unix Specification and POSIX standards help to establish a common set of commands and behaviors across Unix-like operating systems.

Unix-like operating systems

In addition to those listed above, Unix-like operating systems include:

  • 386BSD
  • Arch Linux
  • AIX
  • Android
  • BSD NET/2
  • Debian
  • DragonFly BSD
  • GNU Hurd
  • Illumos
  • iOS
  • IRIX
  • macOS
  • macOS Server
  • MINIX
  • NetBSD
  • NeXTSTEP/OpenSTEP
  • OpenSolaris
  • PlayStation 3 and PlayStation 4 system software.
  • SCO UNIX/Xinuos OpenServer
  • Slackware Linux
  • Sun OS
  • System III/System V
  • UCLinux
  • Ultrix
  • UnixWare
  • Xenix

Kernel, Operating System terms, Variant

  • Unix help and command listing.
  • Unix history.