Hierarchical File System (HFS) is a proprietary file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs. HFS is also referred to as Mac OS Standard, while its successor, HFS Plus, is also called Mac OS Extended.
The resource fork is a fork or section of a file on Apple's classic Mac OS operating system, which was also carried over to the modern macOS for compatibility, used to store structured data along with the unstructured data stored within the data fork.
A filename extension, file name extension or file extension is a suffix to the name of a computer file. The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically delimited from the rest of the filename with a full stop (period), but in some systems it is separated with spaces. Other extension formats include dashes and/or underscores on early versions of Linux and some versions of IBM AIX.
A/UX is a Unix-based operating system from Apple Computer for Macintosh computers, integrated with System 7's graphical interface and application compatibility. It is Apple's first official Unix-based operating system, launched in 1988 and discontinued in 1995 with version 3.1.1. A/UX requires select 68k-based Macintosh models with an FPU and a paged memory management unit (PMMU), including the Macintosh II, SE/30, Quadra, and Centris series.
StuffIt is a discontinued family of computer software utilities for archiving and compressing files. Originally produced for the Macintosh, versions for Microsoft Windows, Linux (x86), and Sun Solaris were later created. The proprietary compression format used by the StuffIt utilities is also termed StuffIt.
MacBinary is a file format that combines the two forks of a classic Mac OS file into a single file, along with HFS's extended metadata. The resulting file is suitable for transmission over FTP, the World Wide Web, and electronic mail. The documents can also be stored on computers that run operating systems with no HFS support, such as Unix or Windows.
Macintosh File System (MFS) is a volume format created by Apple Computer for storing files on 400K floppy disks. MFS was introduced with the original Apple Macintosh computer in January 1984.
A FourCC is a sequence of four bytes used to uniquely identify data formats. It originated from the OSType or ResType metadata system used in classic Mac OS and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives. The idea was later reused to identify compressed data types in QuickTime and DirectShow.
Xsan is Apple Inc.'s storage area network (SAN) or clustered file system for macOS. Xsan enables multiple Mac desktop and Xserve systems to access shared block storage over a Fibre Channel network. With the Xsan file system installed, these computers can read and write to the same storage volume at the same time. Xsan is a complete SAN solution that includes the metadata controller software, the file system client software, and integrated setup, management and monitoring tools.
In a computer file system, a fork is a set of data associated with a file-system object. File systems without forks only allow a single set of data for the contents, while file systems with forks allow multiple such contents. Every non-empty file must have at least one fork, often of default type, and depending on the file system, a file may have one or more other associated forks, which in turn may contain primary data integral to the file, or just metadata.
In the macOS, iOS, NeXTSTEP, and GNUstep programming frameworks, property list files are files that store serialized objects. Property list files use the filename extension .plist, and thus are often referred to as p-list files.
Extended file attributes are file system features that enable users to associate computer files with metadata not interpreted by the filesystem, whereas regular attributes have a purpose strictly defined by the filesystem. Unlike forks, which can usually be as large as the maximum file size, extended attributes are usually limited in size to a value significantly smaller than the maximum file size. Typical uses include storing the author of a document, the character encoding of a plain-text document, or a checksum, cryptographic hash or digital certificate, and discretionary access control information.
The Macintosh Application Environment (MAE) is a software package introduced by Apple Computer in 1994 which allows users of certain Unix-based computer workstations to run application software designed for System 7.
In the Apple macOS operating system, .DS_Store is a file that stores custom attributes of its containing folder, such as folder view options, icon positions, and other visual information. The name is an abbreviation of Desktop Services Store, reflecting its purpose. It is created and maintained by the Finder application in every folder, and has functions similar to the file desktop.ini in Microsoft Windows. Starting with a period . character, it is hidden in Finder and many Unix utilities. Its internal structure is proprietary, but has since been reverse-engineered. Starting at macOS 10.12 16A238m, Finder will not display .DS_Store files.
A Uniform Type Identifier (UTI) is a text string used on software provided by Apple Inc. to uniquely identify a given class or type of item. Apple provides built-in UTIs to identify common system objects – document or image file types, folders and application bundles, streaming data, clipping data, movie data – and allows third party developers to add their own UTIs for application-specific or proprietary uses. Support for UTIs was added in the Mac OS X 10.4 operating system, integrated into the Spotlight desktop search technology, which uses UTIs to categorize documents. One of the primary design goals of UTIs was to eliminate the ambiguities and problems associated with inferring a file's content from its MIME type, filename extension, or type or creator code.
A file format is a standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary or free.
A Unix-like operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell. Although there are general philosophies for Unix design, there is no technical standard defining the term, and opinions can differ about the degree to which a particular operating system or application is Unix-like.
AppleDisk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Finder.
Mac OS is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The Macintosh operating system is credited with having popularized the graphical user interface concept. It was included with every Macintosh that was sold during the era in which it was developed, and many updates to the system software were done in conjunction with the introduction of new Macintosh systems.
