The resource fork is a construct of the Mac OS operating system used to store structured data in a file, alongside unstructured data stored within the data fork. A resource fork stores information in a specific form, such as icons, the shapes of windows, definitions of menus and their contents, and application code (machine code). For example, a word processing file might store its text in the data fork, while storing any embedded images in the same file's resource fork. While the resource fork is probably used the most by applications and other executables, every file is able to have a resource fork. This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... Machine code or machine language is a system of instructions and data directly executed by a computers central processing unit. ...

The Macintosh file system

Further information: Hierarchical File System

Originally conceived and implemented by programmer Bruce Horn, the resource fork became a deeply ingrained characteristic of the Macintosh file system. It is implemented in all of the filesystems used for system drives on the Macintosh (MFS, HFS and HFS Plus). The presence of a resource fork makes it easy to store a variety of additional information, such as allowing the system to display the correct icon for a file and open it without the need for a file extension in the file name. While access to the data fork works like file access on any other operating system — pick a file, pick a byte offset, read some data — access to the resource fork works more like extracting structured records from a database. The data fork is the same as the section used for storing actual data in other operating systems, such as Microsoft Windows. Microsoft Windows also has a concept of "resources," but these are completely different from resources in Mac OS. Hierarchical File System (HFS), is a file system developed by Apple Computer for use on computers 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. ... Bruce Horn, a programmer with Apple Computer, was the creator of the Macintosh Finder. ... Hierarchical File System (HFS), is a file system developed by Apple Computer for use on computers 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. ... See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... This article is about the MFS file system. ... Hierarchical File System (HFS), is a file system developed by Apple Computer for use on computers 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 Plus or HFS+ is a file system developed by Apple Computer to replace their Hierarchical File System (HFS) as the primary file system used on Macintosh computers. ... A filename extension or filename suffix is an extra set of (usually) alphanumeric characters that is appended to the end of a filename to allow computer users (as well as various pieces of software on the computer system) to quickly determine the type of data stored in the file. ... This article is about computing. ... Windows redirects here. ...

The resource fork is sometimes used to store the metadata of a file, although it can also be used for storing the actual data, as was the case with font files in the classic Mac operating systems. Note that the Macintosh file systems also have a separate area for metadata distinct from either the data or resource fork. Being part of the catalogue entry for the file, it is much faster to access this. However, the amount of data stored here is minimal, being just the creation and modification timestamps, the file type and creator codes, fork lengths, and the file name. Metadata is data about data. ...

Some files only have a resource fork. Classic 68k applications are one example, where even the executable code is contained in resources of type 'CODE'. Later PowerPC binaries store the executable code in the data fork.

As resource forks are only supported on the file systems HFS and HFS Plus, they cannot be used on operating systems which use other file systems. At present, HFS is only supported by Mac OS, effectively meaning that only machines running Mac OS can use resource forks. Even in a Mac OS system, resource forks cannot be used if the UFS file system has been installed. In the HFS Plus file system, which is currently the system most commonly used under Mac OS, settings can be made to allow other forks in addition to the data and resource forks, to create a "multi-fork" application, but as forks can make it difficult to exchange files with other operating systems, this feature is not in common use. Even in Mac OS X, resource forks are seldom used anymore. See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... The UNIX file system (UFS) is a file system used by many Unix and Unix-like operating systems. ... // Installation (or setup) of a program (including drivers) is the act and the effect of putting the program in a computer system so that it can be executed. ...

Resource identifiers

Each resource has an OSType identifier (a four byte value) and an ID (a signed 16-bit word), as well as an optional name. There are standardised resource types for dialog boxes ('DITL'), images ('PICT'), sounds ('snd ') — and even for executable binaries ('CODE'), which were until the advent of the PowerPC processor without exception stored in the resource fork. Subroutines for rendering windows are stored in their own type of resources ('WDEF'), subroutines for rendering menus in theirs ('MDEF'), and if there is a type of data you think does not fit any of the standardised categories, you can just as well use a type of your own (eg. 'John') — actually any four characters or 32-bit value can serve as a resource type. This arrangement enabled users to easily customise not only individual applications but also the operating system itself, using tools such as ResEdit to modify the resources of an application file or any of the system files. OSType (also known as FourCC or ResType) is the name of a four-byte type commonly used as an identifier in Mac OS. The four bytes could in principle have any binary value, though they are usually ASCII or characters from the Mac Roman character set. ... Signedness is a property of an integer number used by a compiler to indicate if variables of a numeric type are capable of storing both positive and negative numbers, or just positive. ... A computer word is a measurement of the size of the natural amount of computer memory a particular computer uses. ... Example of dialog box from Microsoft Windows Dialog boxes are special windows which are used by computer programs or by the operating system to display information to the user, or to get a response if needed. ... For the ancient tribe that inhabited what is now Scotland, see the Picts. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... CPU redirects here. ... An example of a graphical user interface in Windows XP, with the My Music window displayed In computing, a window is a visual area, usually rectangular in shape, containing some kind of user interface, displaying the output of and allowing input for one of a number of simultaneously running computer... ResEdit version 2. ...

Within an application or other code, resources can be loaded simply using a combination of their type, ID or name, without regard to how and where they are stored in the resource fork. The client is returned a Handle to the loaded resource which can then be accessed like any other heap-based data. The OS component that facilitates this is the Resource Manager. In addition to abstracting the details of the data storage from the data itself, the Resource Manager also arranges sets of open resource forks into a stack, with the most recently opened file on top. When trying to load a resource, it will look in the top of the stack first, (perhaps the current document's resource fork), then the next one down (the application's resource fork), then the next one (system resource forks). This arrangement is very powerful — it permits local resources to override more global ones lower down — so an application can provide its own icons or fonts in place of the standard system ones, for example. It also allows an application to load resources from the system using the same API as any other resource, without regard to where or how that resource is stored — to the application, all resources are equally available and easy to use. The system reserves resource IDs in a certain range to help avoid resource conflicts arising from this. Resource Manager APIs allow the programmer to manipulate the stack and modify the search behaviour. This article is about a general notion of reference in computing. ...

Editing resource forks

As the resource fork can be edited with a resource editor such as ResEdit, it can be used to localize and customize software. In addition, most resource editors allow visual editing of data. In Mac OS X, it is possible to use resources when developing an application. However, if the application may need to be used in UFS, it is also possible to configure it so that the entire resource fork is moved to the data fork, using the Raw Resource File setting. The integrated development environments distributed for free by Apple Inc., which include MPW and Apple Developer's Tools, include a compiler called Rez. This uses a dedicated language, also called Rez, which can be used to create a resource fork by compiling source code. A decompiler, DeRez, which can be used to change a resource fork back into Rez code is also included. ResEdit version 2. ... Look up localisation, localization in Wiktionary, the free dictionary. ... Tailoring specifically to an individual. ... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... The UNIX file system (UFS) is a file system used by many Unix and Unix-like operating systems. ... An integrated development environment (IDE), also known as integrated design environment and integrated debugging environment, is a programming environment that has been packaged as an application program,that assists computer programmers in developing software. ... Apple Inc. ... MPW version 3. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... Source code (commonly just source or code) is any series of statements written in some human-readable computer programming language. ...

In the structure of the resource fork, there is a piece of data called a "resource map" which stores the positions of resource data items. This can be used to allow random access to resource data based on the defined IDs and names. The resource fork can be thought of as consisting of essentially two objects, the resource map and the resource data itself, but in fact each data type is a hierarchical structure which stores multiple items of data. The format in which the information in the resource data is stored is defined based on the types of information, which are known as "resource types." Resource data often references other types of data. In computer science, random access is the ability to access a random element of a group in equal time. ...

To view the resource fork in the Terminal application. Append "/..namedfork/rsrc" to your command. e.g., take the command "ls -aol IMG_0593.jpg" then append the resource fork viewing suffix "ls -aol IMG_0593.jpg/..namedfork/rsrc" to view the ls -aol command information of the resource fork of file "IMG_0593.jpg"

How a resource fork is accessed

A resource fork is accessed via an API called the Resource Manager. API may refer to: In computing, application programming interface In petroleum industry, American Petroleum Institute In education, Academic Performance Index This page concerning a three-letter acronym or abbreviation is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

1. When a resource fork is accessed, data including the start position and length of the resource data and resource map is read in from the header.
2. If a resource type to read in has been specified, a check is performed to make sure that type is present in the resource list, and the number of items of data containing that type and their offsets in the resource reference list from the start position of the resource map is found.
3. The resource ID, the offset of the resource name, the resource properties, and the offset of the data from the start position of the resource data is found.
4. If resource data with the specified ID or name is present in the resource data, the offset obtained above is accessed, the data length is found, and all the data stored there is read in, and returned as the return value.

Data types in a resource fork

The smallest elements making up a resource fork are called data types. There are several data types. After a resource fork is accessed, its contents can be found by reading it in as appropriate for the data types defined in advance. Placing definitions inside the program stating how data is to be treated makes it possible to store resources called TMPL resources as well. Using this method increases the visibility of the data when viewed with a program such as ResEdit, making later editing simpler. As the Macintosh platform originated with Motorola-based processors (68k and PPC), the data is serialized to disk in big endian format. When integers or any other data are represented with multiple bytes, there is no unique way of ordering of those bytes in memory or in a transmission over some medium, and so the order is subject to arbitrary convention. ...

The following is a list of the major data types, in alphabetical order.

C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... A creator code is a mechanism used in pre-Mac OS X versions of the Macintosh operating system to link a data file to the application program which created it, in a manner similar to file extensions in other operating systems. ...

Major resource types

Version is a state of an object or concept that varies from its previous state or condition. ...

Major resource editors

• ResEdit (Distributed free of charge by Apple. Can be used for visual editing of resource data. If the structure of data is known, it can display a range of different types of data in a visual format.)
• Resorcerer (Expensive, but popular, as it can be used for visual editing of many more types of data than ResEdit.)
• HexEdit (A binary editor, which in fact is normally used more for editing the data fork rather than the resource fork.)
• ResKnife (Open‐source editor for Mac OS X)

ResEdit version 2. ... ResKnife is a resource editor for the Macintosh. ...

Compatibility problems

The complexity of programming with resource forks has led to compatibility problems with other filesystems in the past. In order to transmit a Macintosh file over a network or other medium, the data and resource forks must be serialized together. A number of file formats, such as MacBinary and BinHex, have been used to implement this. Command-line system tools SplitForks and FixupResourceForks allow manual flattening and merging of resource forks. In addition, a file server seeking to present filesystems to Macintosh clients must accommodate the resource fork as well as the data fork of files; UNIX servers usually implement this with hidden directories. Due to the Mac OS forked file structure, transferring Mac OS files to non-Macintosh computers is problematic. ... BinHex, short for binary-to-hexadecimal, is an ASCII armoring system that was used on the Mac OS for sending binary files through E-mail. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ...

Older applications written with the Carbon API have a potential issue when being ported to the current Intel Macs. While the Resource Manager and operating system know how to correctly deserialize data for common resources like "snd " or "moov," resources created using TMPL resources have to be manually byte swapped to ensure file interoperability between PPC and Intel-based versions of an application. (While the resource map and other implementation details are big endian, the Resource Manager by itself doesn't have any knowledge of the contents of a generic resource, and so cannot automatically perform the byte swapping.) Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ...

Until the advent of Mac OS X v10.4, the standard UNIX command line utilities in Mac OS X (such as cp and mv) did not respect resource forks. To copy files with resource forks, one had to use ditto or CpMac and MvMac. Mac OS X version 10. ...

Other operating systems

The concept of a resource is now largely universal in all modern operating systems. However, the concept of the resource fork remains a Mac-only one. Most operating systems used a binary file containing resources, which is then "tacked onto" the end of an existing program file. This solution is used on Microsoft Windows for instance, and similar solutions are used with the X Window System, although the resources are often left as a separate file. Windows redirects here. ... “X11” redirects here. ...

Although the Windows NT NTFS can support forks (and so can be a file server for Mac files), the native feature providing that support, called an alternate data stream, has never been used extensively — certainly not as a true resource fork. However, Windows operating system features (such as the standard Summary tab in the Properties page for non-Office files) and Windows applications are using them more often now, and Microsoft is developing a next-generation file system that has this sort of feature as basis. Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ... In computer file systems, a fork is additional data associated with a file system object. ... It has been suggested that Microsoft Rave be merged into this article or section. ...

Early versions of the BeOS implemented a database within the filesystem, which could be used in a manner analogous to a resource fork. Performance issues led them to change this in later releases to a system of complex filesystem attributes. Under this system resources were handled in a fashion somewhat more analogous to the Mac. BeOS is an operating system for personal computers which began development by Be Inc. ...

AmigaOS does not use forked files. Its executable files are internally divided into a modular structure of large pieces (hunk) capable of storing code, data, and additional information. Similarly, data and project files have a chunk structure codified in the IFF standard. Other file types are stored similarly to other operating systems. Though not strictly a resource fork, AmigaOS stores meta data in files known as .info files. .info files can be identified by the .info extension; for example, if you save a project to a disk, two files will be saved, MyProject and MyProject.info. MyProject would be the actual project data and MyProject.info would contain the project icon, information regarding which program is needed to open the project (since there is no application binding in AmigaOS), special project options and any user comments. .info files are invisible on the Amiga's desktop (Workbench). The icon on the desktop, taken from the .info itself, is the interface metaphor through which the user interacts both with the project itself and its associated .info file. A dialog box accessible by right-clicking the icon allows the user to see and modify the metadata present in the .info file. .info files can be seen as individual files in the Command line interface or a File manager. Modern AmigaOS clones (AROS, MorphOS and AOS4) inherit the structure (complete with metadata) of the .info files of older AmigaOS versions, and can also accept standard PNG graphic files as icon bitmaps in their .info files. AmigaOS is the default native operating system of the Amiga personal computer. ... An executable or executable file, in computer science, is a file whose contents are meant to be interpreted as a program by a computer. ... Look up hunk in Wiktionary, the free dictionary. ... Chunky is a method of frame buffer organization in computer graphics. ... Interchange File Format (IFF), is a generic file format originally introduced by the Electronic Arts company in 1985 (in cooperation with Commodore-Amiga) in order to ease transfer of data between software products produced by different companies. ... AmigaOS is the default native operating system of the Amiga personal computer. ... Amiga Workbench (1985) Workbench is the name given to both the core AmigaOS software that is not stored in the Kickstart ROM (the Workbench disk), and also the native graphical shell for the Amiga computer. ... The user interface is the part of a system exposed to users. ... An Interface Metaphor is an icon used to metaphorically explain a more abstract concept. ... This article or section does not adequately cite its references or sources. ... For the Windows 3. ... What is AROS? AROS (Amiga Research Operating System) is an open source implementation of the AmigaOS 3. ... MorphOS is a mixed proprietary and open source operating system produced for the Pegasos PowerPC (PPC)-processor-based computer, most models of PPC-accelerated classic Amiga computers, and the EFIKA PPC consumer device. ... PNG (Portable Network Graphics), sometimes pronounced as ping, is a relatively new bitmap image format that is becoming popular on the World Wide Web and elsewhere. ...

NeXT operating systems NeXTSTEP and OPENSTEP, and its successor, Mac OS X, and other systems like RISC OS implemented another solution. Under these systems the resources are left in an original format, for instance, pictures are included as complete TIFF files instead of being encoded into some sort of container. These resources are then placed in a directory along with the executable code and "raw data". The directory (called a "bundle" or "application directory") is then presented to the user as the application itself. This solution provides all of the same functionality as the resource fork, but allows the resources be easily manipulated by any application – a "resource editor" (like ResEdit) is not needed. From the command line interface, the bundle appears to be a normal directory. This approach was not an option on the original Macintosh OS, since the file system (MFS) did not support folders/directories. Mac OS X does retain the classic Resource Manager API as part of its Carbon libraries for backward compatibility. However, the resources themselves can now be stored in separate data files within the filesystem — the Resource Manager now hides this implementation change from the client code. For other meanings, see Next. ... NEXTSTEP is the original object-oriented, multitasking operating system that NeXT Computer, Inc. ... OPENSTEP on Windows NT. OpenStep is an object-oriented API specification for an object-oriented operating system that uses any modern operating system as its core, principally developed by NeXT with Sun Microsystems. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... This article does not cite any references or sources. ... This article is about TIFF, the computer image format. ... Under NEXTSTEP, Mac OS X and GNUstep, a bundle is a directory that allows related resources such as software code to be grouped together. ... In RISC OS and the ROX Desktop, an application directory is a grouping of software code, help files and resources that together comprise a complete software package but are presented to the user as a single file. ... ResEdit version 2. ... This article or section does not adequately cite its references or sources. ... Apple marketed its operating system software as Mac OS, beginning in 1997. ... This article is about the MFS file system. ... API and Api redirect here. ... Carbon is the codename of Apple Computers APIs for the Macintosh operating system, which permits a good degree of backward compatibility between source code written to run on the classic Mac OS, and the newer Mac OS X. The APIs are published and accessed in the form of C...

External links

• Description of the Resource File Format
• Apple Developer Resource Library: Resource Manager Reference
• Apple Developer Resource Library: Resource Management, Bundles
• Apple Docs: Disable .DS_Store Files On Network Disks
• osxutils - open-source resource-fork-aware command line utilities for Mac OS X
• The Grand Unified Model - History of the resource fork, from folklore.org