A path (or filepath, file path, pathname, or similar) is a string that uniquely identifies an item in a hierarchical file system. Generally, a path is composed of directory names, special format specifiers, and optionally a filename, all separated by delimiters. This delimiter can vary by operating system, but popular, modern systems use the slash/, backslash\, or colon:.
A path can be either relative or absolute. A relative path is a path in relation to another, most often the working directory. An absolute path indicates a location regardless of the current directory, and therefore does not depend on context like a relative path does.
Paths are also essential in the construction of URLs.
Around 1970, Unix introduced the slash / as its directory separator.
Originally, MS-DOS did not support directories. When adding the feature, using the Unix standard of a slash was not a good option since many existing commands used a slash as the switch prefix (i.e., dir /w). In contrast, Unix uses the dash - as the switch prefix. The backslash \ was ultimately chosen instead for its similarity to the slash and not conflicting with existing commands. This convention continued into Windows. However, some areas of Windows do accept or understand Unix-style slashes also, such as PowerShell.[2][3]
Summary of systems
The following table describes the syntax of paths in notable operating systems:
In Seed7, all paths use the Unix path convention, regardless of operating system. Under Windows, the path /c/Users/ would be mapped to C:\Users\.[19]
In Unix
Most Unix-like systems use a similar syntax.[20]POSIX allows treating a path beginning with two slashes in an implementation-defined manner,[21] though in other cases systems must treat consecutive slashes as one.[22]
Many applications on Unix-like systems (for example, scp, rcp, and rsync) use resource definitions such as hostname:/directorypath/resource, or URI schemes with the service name (here 'smb'), like smb://hostname/directorypath/resource.
In macOS
When macOS was being developed, it inherited some pathname choices from Classic Mac OS and the Unix-likeNeXTSTEP. The classic Mac OS uses a : while Unix and Unix-like systems use a / as the path delimiter. As a solution, to preserve compatibility for software and familiarity for users, and to allow disk file systems to be used both by the classic Mac OS and macOS, some portions of macOS convert between colons and slashes in pathnames;[23] for example, the HFS+ file system, from the classic Mac OS, converts colons in file names to slashes and, when reading a directory, converts slashes in filenames to colons,[24] as and the Carbon toolkit converts colons in pathnames to slashes and slashes in path names to colons, and converts them back when providing filenames and pathnames to the caller.[24]
DOS device paths, such as \\?\C:\File or \\.\UNC\Server\Volume\File. The first, \\?\ skips path normalization. The second, \\.\ uses the raw device namespace.[25][26]
In the Windows API, file I/O functions automatically convert / into \ (except when using the \\?\ prefix). Unless the \\?\ prefix is used, paths are limited to the length defined by MAX_PATH, which is 260.[27]
PowerShell allows slash-interoperability for backwards-compatibility:[28]
Japanese and Korean versions of Windows often displayed the '¥' character or the '₩' character instead of the directory separator. This is because while in ANSI codepages, the character at 0x5C was the backslash, and in Japanese and Korean codepages, 0x5C was the yen and won signs, respectively. Therefore, when the character for a backslash was used, other glyphs appeared.[29]
Universal Naming Convention
The Microsoft Universal Naming Convention (UNC, uniform naming convention, or network path), is a syntax to describe the location of a network resource, such as a shared file, directory, or printer. A UNC path has the general form:
\\ComputerName\SharedFolder\Resource
Some Windows interfaces allow or require UNC syntax for WebDAV share access, rather than a URL. The UNC syntax is extended with optional components to denote use of SSL and TCP/IP port number. Thus, the WebDAV URL of https://hostname[:port]/SharedFolder/Resource becomes \\hostname[@SSL][@port]\SharedFolder\Resource.[30]
When viewed remotely, the "SharedFolder" may have a name different from what a program on the server sees when opening "\SharedFolder". Instead, the SharedFolder name consists of an arbitrary name assigned to the folder when defining its "sharing".
Since UNCs start with two backslashes, and the backslash is also used for escape sequences and in regular expressions, cases of leaning toothpick syndrome may arise. An escaped string for a regular expression matching a UNC begins with 8 backslashes \\\\\\\\ because the string and regular expression both require escaping. This can be simplified by using raw strings, such as @"\\\\" in C#, r'\\\\' in Python, or qr{\\\\} in Perl.
See also
basename– Shell command for extracting the last name from a path
Device file– Interface to a device driver that appears in a file system as if it were an ordinary file
↑ [prefix] may be a number (0–31), * (boot volume) or @ (AppleShare home directory)
References
↑ Daley, R.C.; Neumann, P.G. (1965). "A general-purpose file system for secondary storage". Proceedings of the November 30--December 1, 1965, fall joint computer conference, Part I on XX - AFIPS '65 (Fall, part I). Vol.Part I. pp.213–229. doi:10.1145/1463891.1463915. S2CID16236414.
↑ The AmigaDOS Manual. Produced by Commodore-Amiga, Inc. Bantam Computer Books. February 1986. pp.6–16. ISBN978-0-553-34294-9.{{cite book}}: CS1 maint: others (link)
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