UNIXcompliant

Unixcompliant is an informal designation used in software development to indicate that a program, library, or tool adheres to Unix-like conventions and is designed to operate well on Unix and Unix-like systems. It is not a formal standard or certification, and there is no official governing body that issues Unixcompliant status.

The designation suggests compatibility with POSIX interfaces and with the traditional Unix toolkit, including small, modular programs that can be combined via pipes, text-based interfaces, and predictable exit codes. In practice, Unixcompliant software tends to strive for portability across Unix-like platforms such as Linux, macOS, and BSD variants, and avoids platform-specific assumptions whenever possible.

Typical indicators include adherence to POSIX function interfaces in portable libraries, use of standard input/output streams and conventional shell behavior, reliance on plain-text configuration, and respect for standard filesystem layout and environment variables. It also implies that the software can be embedded or composed with other Unix tools without requiring bespoke wrappers.

Limitations: because the label is informal, there is no uniform test suite or certification. Some Unixcompliant software may exceed POSIX in terms of features, while others may sacrifice strictness in favor of practical usability on a subset of systems. The term does not guarantee support on non-Unix platforms.

Relation to the Unix philosophy: Unixcompliant design aligns with the idea of building simple, interoperable tools that do one thing well and work together through standard interfaces.

See also: POSIX, Unix philosophy, portable software, Unix-like systems.