HP-UX

HP-UX (from "Hewlett Packard Unix") is a discontinued proprietary implementation of the Unixoperating system developed by Hewlett Packard Enterprise, now out of standard support (Mature Support on HPE Integrity without Sustaining Engineering through at least 2028); the final versions support HPE Integrity Servers, based on Intel's Itanium architecture. It is based on Unix System V (initially System III) and first released in 1984.

Earlier versions of HP-UX supported the HP Integral PC and HP 9000 Series 200, 300, and 400 computer systems based on the Motorola 68000 series of processors, the HP 9000 Series 500 computers based on HP's proprietary FOCUS architecture, and later HP 9000 Series models based on HP's PA-RISCinstruction set architecture. HP-UX was the first Unix to offer access-control lists for file access permissions as an alternative to the standard Unix permissions system. HP-UX was also among the first Unix systems to include a built-in logical volume manager.

Following the discontinuation of Itanium processors, support for HP-UX ended on December 31, 2025. HP-UX 11i (the latest then-supported version) is certified to The Open Group's older UNIX 03 standard. Previous releases were certified to the UNIX 95 standard.