The Services menu (or simply Services) is a

user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...

element in

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

. The services are programs that accept input from the user selection, process it, and optionally put the result back in the clipboard. The concept originated in the

NeXTSTEP NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT Computer in the late 1980s and early 1990s and was initially used for its range of propri ...

operating system, from which it was carried over into

and

GNUstep GNUstep is a free software implementation of the Cocoa (formerly OpenStep) Objective-C frameworks, widget toolkit, and application development tools for Unix-like operating systems and Microsoft Windows. It is part of the GNU Project. GNUste ...

. Similar features can be emulated on other operating systems.

macOS

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...

advertises the Services menu in connection with other features of its operating system. For example, it's possible to

desktop search Desktop search tools search within a user's own computer files as opposed to searching the Internet. These tools are designed to find information on the user's PC, including web browser history, e-mail archives, text documents, sound files, images ...

for a piece of text by selecting it with the mouse and using the service from

Spotlight Spotlight or spot light may refer to: Lighting * Spot lights, automotive auxiliary lamps * Spotlight (theatre lighting) * Spotlight, a searchlight * Stage lighting instrument, stage lighting instruments, of several types Art, entertainment, an ...

. Other central services are Grab for taking screenshots, and the system

spell checker In software, a spell checker (or spelling checker or spell check) is a software feature that checks for misspellings in a text. Spell-checking features are often embedded in software or services, such as a word processor, email client, electronic ...

. The concept is similar to a

GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...

equivalent of a

Unix pipe In Unix-like computer operating systems, a pipeline is a mechanism for inter-process communication using message passing. A pipeline is a set of processes chained together by their standard streams, so that the output text of each process (''s ...

, allowing arbitrary data to be processed and passed between programs. Services can be implemented as application services, which expose a portion of the functionality of an application to operate on selected data, usually without displaying an interface. In its developer documentation, Apple recommends that applications use services to provide features that are "generally useful", giving as an example a

Usenet Usenet () is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it wa ...

client providing ROT13 encryption as a service. Standalone services may also be created without a host application. Their simple, one-purpose nature and the fact that they don't require a GUI to be designed makes writing standalone services popular beginner's macOS programming projects. Since many applications install their entries without asking the user, the macOS services menu tends to clog up with dozens of entries quickly. Most users only will ever use a small subset of the possible options, therefore cutting down and customizing the menu makes it both faster and more pleasant to use. Prior to

Mac OS X Snow Leopard Mac OS X Snow Leopard (version 10.6) is the seventh major release of macOS, Apple's desktop and server operating system for Macintosh computers. Snow Leopard was publicly unveiled on June 8, 2009 at Apple’s Worldwide Developers Conference. ...

, third party software is required to do this; in Snow Leopard, the Services menu can be customized from the Keyboard pane of

System Preferences System Settings (System Preferences on macOS Monterey and earlier) is an application included with macOS. It allows users to modify various system settings, which are divided into separate Preference Panes. The System Settings application w ...

Emulation

From the point of view of software, the Services menu is a means of

inter-process communication In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categoriz ...

. To the user, it is an interface for executing actions on selected data. The emulation of the Services menu is based on the fact that there are several ways this can be achieved in an operating system. Even in macOS, there is an alternative system called the

context menu A context menu (also called contextual, shortcut, and pop up or pop-up menu) is a menu in a graphical user interface (GUI) that appears upon user interaction, such as a right-click mouse operation. A context menu offers a limited set of choic ...

handler, which is carried over from

classic Mac OS Mac OS (originally System Software; retronym: Classic 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. ...

. In the

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wi ...

, any data selected in an application is available to all other programs. Thus the Services menu can be an application which retrieves the current selection, and lets the user choose an action. Missing is the part about returning the processed data back to the originating application. Instead, the service can open a new window to show the results. Alternatively, the service could replace the current cut buffer with the results of the operation, leaving the user only to perform a paste (since different toolkits implement copy/select and paste commands differently, and probably not under external program control).

References

{{Reflist

External links

Introduction to System Services
at Apple Developer Connection
Services menu emulation for Linux/Unix with PyGTK
NeXT MacOS user interface GNUstep