A Unix-like system behaves like a Unix system while not being certified to any version of the Single UNIX Specification. The term can include free and open-source operating systems inspired by Bell Labs' Unix and proprietary work-alike. The Open Group owns the UNIX trademark. UNIX name can be only used when certified by the Open Group. They do not support the construction "Unix-like," and consider it a misuse of their trademark.
List of certified UNIX operating systems
- macOS from Apple
- HP-UX from HP/HPE
- AIX from IBM
- SunOS/Solaris from Oracle
List of "Unix-like" operating systems