HP-UX (Hewlett Packard UniX) is Hewlett-Packard's proprietary implementation of the Unix operating system, based on System V (initially System III). It runs on their PA-RISC range of processors and Intel's Itanium processor, and was also available for later Apollo/Domain systems. Earlier versions also ran on the HP 9000 Series 200, 300, and 400 computer systems based on the Motorola 68000 series of processors, as well as the HP 9000 Series 500 computers based on HP's proprietary FOCUS processor architecture.
HP-UX was the first Unix to use access control lists for file access permissions rather than the standard Unix permissions system. HP-UX was also among the first Unix systems to include a built-in logical volume manager. HP has had a long partnership with VERITAS, and they use VxFS as their primary file system. For legacy as well as technical reasons, however, the file system used for the boot kernel has remained Hi Performance FileSystem (HFS; a variant of UFS) and so this older technology has continued to receive support from HP.
As of HP-UX 11i v2 release, the operating system will scale as follows:
