File association

Last updated

In computing, a file association associates a file with an application capable of opening that file. More commonly, a file association associates a class of files (usually determined by their filename extension, such as .txt ) with a corresponding application (such as a text editor).

Contents

Associations and verbs

A single file extension may have several associations for performing various actions, also known as verbs. Some of the common verbs are:

A picture, for example, may be associated with these words so that open opens the picture in an image viewer, edit opens up an image editing program and print sends the picture to a printer.

Implementations

Most operating systems support file associations in some form or the other. For example, opening a file from a file manager usually invokes the open verb in order to open the file with its associated application. The "open" verb invokes the associated application program, which reads the file or document and presents it to the user for viewing, and possibly for editing or other action.

Additional actions such as print are usually accessed via a right-click context menu. A mechanism for modifying associations is also usually present. An example for this is the Open With option in the Windows Shell.

Microsoft Windows

The Microsoft Windows series of operating systems, beginning with Windows 3.x supports file extension-based associations. [1] Associations are stored in registry [2] as sets of verbs for each file extension. Older versions supported open associations stored in WIN.INI. File associations can be displayed and edited using the assoc command and with the help of the ftype command it is possible to create association between file type and application which will open files of this type. [3] [4]

The Windows shell invokes file association actions through COM, drag and drop, command line calls or through Dynamic Data Exchange. Advanced features of Microsoft Windows file associations included manually defining a new file extension with any number of associated actions, a primary default action, showing extensions only for specific file types, customizing the file type icon and description and customizing associated MIME type and their handling (how to handle file types for files downloaded or directly opened from within the Internet Explorer browser). The ability to configure advanced file association functionality, however, was removed in Windows Vista and later operating systems.

Linux

Linux-based GUIs, such as KDE and GNOME, support MIME type-based associations.[ citation needed ] For example, the MIME type text/plain would be associated with a text editor. This association is generally accomplished through the freedesktop.org Shared MIME database (for determining the MIME type of a file) and the Desktop Entry specification (for determining which application to open the file with). [5]

Mac OS

The Classic Mac OS used type codes and creator codes to associate each file with its corresponding application, regardless of file extension. The more recent macOS also supports file extension–based associations.

Application bundles in macOS declare supported file types in their Info.plist file. For each of these specified types, a Uniform Type Identifier is given, along with a list of 'tags' which define how a file or data of this type could be identified. For example, the JPEG type is defined with a UTI of 'public.jpeg', and tagged with the extensions 'jpg' and 'jpeg', the MIME type 'image/jpeg' and the type code 'JPEG'. [6]

The operating system uses this information to generate a list of applications which are able to open each type. Within Finder (software) each file will be identified with a UTI and open with the default application for that type. The user may also select from a list of other applications which support the type.

Using this system, types are also associated with data for which there is no file name or the file extension is missing. This includes pasteboard data and data streaming over a protocol such as HTTP where a MIME type has been given.

See also

Related Research Articles

Multipurpose Internet Mail Extensions (MIME) is a standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs. Message bodies may consist of multiple parts, and header information may be specified in non-ASCII character sets. Email messages with MIME formatting are typically transmitted with standard protocols, such as the Simple Mail Transfer Protocol (SMTP), the Post Office Protocol (POP), and the Internet Message Access Protocol (IMAP).

Object Linking and Embedding (OLE) is a proprietary technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control Extension (OCX), a way to develop and use custom user interface elements. On a technical level, an OLE object is any object that implements the IOleObject interface, possibly along with a wide range of other interfaces, depending on the object's needs.

Tag Image File Format or Tagged Image File Format, commonly known by the abbreviations TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word processing, optical character recognition, image manipulation, desktop publishing, and page-layout applications. The format was created by the Aldus Corporation for use in desktop publishing. It published the latest version 6.0 in 1992, subsequently updated with an Adobe Systems copyright after the latter acquired Aldus in 1994. Several Aldus or Adobe technical notes have been published with minor extensions to the format, and several specifications have been based on TIFF 6.0, including TIFF/EP, TIFF/IT, TIFF-F and TIFF-FX.

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.

A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists stored as data within a computer file system.

<span class="mw-page-title-main">CUPS</span> Computer printing system

CUPS is a modular printing system for Unix-like computer operating systems which allows a computer to act as a print server. A computer running CUPS is a host that can accept print jobs from client computers, process them, and send them to the appropriate printer.

<span class="mw-page-title-main">DIGITAL Command Language</span> Command language adopted by several operating systems (OSs)

DIGITAL Command Language (DCL) is the standard command language adopted by many of the operating systems created by Digital Equipment Corporation. DCL had its roots in IAS, TOPS-20, and RT-11 and was implemented as a standard across most of Digital's operating systems, notably RSX-11 and RSTS/E, but took its most powerful form in VAX/VMS. DCL continues to be developed by VSI as part of OpenVMS.

MHTML, an initialism of "MIME encapsulation of aggregate HTML documents", is a Web archive file format used to combine, in a single computer file, the HTML code and its companion resources that are represented by external hyperlinks in the web page's HTML code. The content of an MHTML file is encoded using the same techniques that were first developed for HTML email messages, using the MIME content type multipart/related. MHTML files use an .mhtml or .mht filename extension.

In computing, a file shortcut is a handle in a user interface that allows the user to find a file or resource located in a different directory or folder from the place where the shortcut is located. Similarly, an Internet shortcut allows the user to open a page, file or resource located at a remote Internet location or Web site.

The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for digital documents and data sets.

Long filename (LFN) support is Microsoft's backward-compatible extension of the 8.3 filename naming scheme used in MS-DOS. Long filenames can be more descriptive, including longer filename extensions such as .jpeg, .tiff, and .html that are common on other operating systems, rather than specialized shortened names such as .jpg, .tif, or .htm. The standard has been common with File Allocation Table (FAT) filesystems since its first implementation in Windows NT 3.5 of 1994.

An image file format is a file format for a digital image. There are many formats that can be used, such as JPEG, PNG, and GIF. Most formats up until 2022 were for storing 2D images, not 3D ones. The data stored in an image file format may be compressed or uncompressed. If the data is compressed, it may be done so using lossy compression or lossless compression. For graphic design applications, vector formats are often used. Some image file formats support transparency.

The Portland Project is an initiative by freedesktop.org aiming at easing the portability of application software between desktop environments and kernels by designing cross-platform APIs and offering implementations thereof as libraries to independent software vendors (ISVs).

The clipboard is a buffer that some operating systems provide for short-term storage and transfer within and between application programs. The clipboard is usually temporary and unnamed, and its contents reside in the computer's RAM.

In information and communications technology, a media type, content type or MIME type is a two-part identifier for file formats and content formats. Their purpose is comparable to filename extensions and uniform type identifiers, in that they identify the intended data format. They are mainly used by technologies underpinning the Internet, and also used on Linux desktop systems.

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 batch file is a script file in DOS, OS/2 and Microsoft Windows. It consists of a series of commands to be executed by the command-line interpreter, stored in a plain text file. A batch file may contain any command the interpreter accepts interactively and use constructs that enable conditional branching and looping within the batch file, such as IF, FOR, and GOTO labels. The term "batch" is from batch processing, meaning "non-interactive execution", though a batch file might not process a batch of multiple data.

Sidecar files, also known as buddy files or connected files, are computer files that store data which is not supported by the format of a source file.

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.

In computing, ftype is a command-line utility on Microsoft Windows that is used to display or change the link between a file type and an executable program.

References

  1. "Windows 3.x Features".
  2. HKEY_CLASSES_ROOT Key
  3. Microsoft TechNet Assoc article on assoc
  4. Microsoft TechNet Ftype article on ftype
  5. "Association between MIME types and applications". specifications.freedesktop.org. Retrieved 2 December 2024.
  6. Mac OS X Reference Library - Uniform Type Identifier Concepts

Further reading

  1. "Implementing a Custom File Format". Microsoft Developer Network Library. Microsoft Corporation. 9 November 2010. Retrieved 5 December 2010.
  2. "File Associations". KDE Documentation. KDE. 11 November 2016. Retrieved 30 May 2020.