Alias (Mac OS)

In Mac OS System 7 and later, an alias is a small file that represents another object in a local, remote, or removablefile system and provides a dynamic link to it; the target object may be moved or renamed, and the alias will still link to it (unless the original file is recreated; such an alias is ambiguous and how it is resolved depends on the version of macOS). In Windows, a "shortcut", a file with a .lnk extension, performs a similar function, but is not dynamic.

It is similar to the Unix symbolic link, but with the distinction of working even if the target file moves to another location on the same disk (in this case it acts like a hard link, but the source and target of the link may be on different filesystems). As a descendant of BSD, macOS supports Unix symbolic (and hard) links as well.

An alias acts as a stand-in for any object in the file system, such as a document, an application, a folder, a hard disk, a network share or removable medium or a printer. When double-clicked, the computer will act the same way as if the original file had been double-clicked. Likewise, choosing an alias file from within a 'File Open' dialog box would open the original file. The purpose of an alias is to assist the user in managing large numbers of files by providing alternative ways to access them without having to copy the files themselves. While a typical alias under the classic Mac OS was small, between 1 and 5 KB, under macOS it can be fairly large, more than 5000 KB for the alias to a folder.

An alias is a dynamic reference to an object. The original may be moved to another place within the same filesystem, without breaking the link. The operating system stores several pieces of information about the original in the resource fork of the alias file. Examples of the information used to locate the original are:

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