Apath (orfilepath,file path,pathname, or similar) is astring that uniquely identifies an item in ahierarchical file system. Generally, a path is composed of directory names, special format specifiers, and optionally afilename, all separated bydelimiters. This delimiter can vary by operating system, but popular, modern systems use theslash/,backslash\, orcolon:.

Thecase-sensitivity of individual path components will vary based onoperating system, or based on options specified at the time of a file system'screation orfirst use. In practice, this means that for acase-sensitive system, path components namedcomponent1 andComponent1 can coexist at the same level in the hierarchy, whereas for acase-insensitive file system, they cannot (an error will occur). macOS and Windows' native file systems are case-insensitive by default, whereas typical Linux file systems are case-sensitive.^[1][2][3]

A path can be eitherrelative orabsolute. A relative path is a path in relation to another, most often theworking directory. An absolute path indicates a location regardless of the current directory; that is, it specifies all path components starting from the file system'sroot, and does not depend on context like a relative path does.

Paths are also essential for locating hierarchically-organized network resources, as seen inURLs andUNC paths.

Multics first introduced ahierarchical file system with directories (separated by ">") in the mid-1960s.^[4]

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 theswitch 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 intoWindows. However, some areas of Windows do accept or understand Unix-style slashes also, such asPowerShell.^[5][6]

The following table describes the syntax of paths in notable operating systems:

Most programming languages use the path representation of the underlying system, but some may also be system-independent.

For instance, this C code is system-dependent and may fail on opposing systems:

uxFile=fopen("project/readme.txt","r")// Fails on WindowswinFile=fopen("C:\\Program Files\\bin\\config.bat","r")// Fails on Unix

• InJava, theFile.separator field stores the system-dependent separator.^[20] Some functions preclude the need for the separator entirely.

importjava.io.File;importjava.nio.file.Path;importjava.nio.file.Paths;// ...Filefile=newFile("path"+File.separator+"file.txt");Pathpath=Paths.get("path","file.txt");

• InPython, thepathlib module offers system-independent path operations.^[21]

frompathlibimportPathwith(Path("path")/"to"/"file.txt").open()asopen_file:...

Most Unix-like systems use a similar syntax.^[22]POSIX allows treating a path beginning with two slashes in an implementation-defined manner,^[23] though in other cases systems must treat consecutive slashes as one.^[24]

Many applications on Unix-like systems (for example,scp,rcp, andrsync) use resource definitions such ashostname:/directorypath/resource, orURI schemes with the service name (here 'smb'), likesmb://hostname/directorypath/resource.

WhenmacOS was being developed, it inherited some pathname choices fromClassic Mac OS and theUnix-likeNeXTSTEP. The classic Mac OS uses a: whileUnix 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;^[25] 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,^[26] as and theCarbon 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.^[26]

DOS and Windows have no single root directory; a root exists for each storage drive, indicated with a drive letter or through UNC.

Directory and file name comparisons are case-insensitive: "test.TXT" would match "Test.txt".^[27]

Windows understands the following kinds of paths:

• Local paths, such asC:\File.
• Universal naming convention (UNC).
• DOS device paths, such as\\?\C:\File or\\.\UNC\Server\Volume\File. The first,\\?\ skips path normalization. The second,\\.\ uses the raw device namespace.^[27][28]

In theWindows 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 byMAX_PATH, which is 260.^[29]

PowerShell allows slash-interoperability for backwards-compatibility:^[30]

PSC:\>Get-Content-Path"C:/path/to/file.txt"Hereissometextwithinafile

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.^[31]

The MicrosoftUniversal Naming Convention (UNC,uniform naming convention, ornetwork 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 forWebDAV 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 ofhttps://hostname:443/SharedFolder/Resource becomes\\hostname@SSL@443\SharedFolder\Resource.^[32]

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 forescape sequences and inregular expressions, cases ofleaning 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 usingraw strings, such as@"\\\\" in C#,r'\\\\' inPython, orqr{\\\\} inPerl.

• 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
• dirname – Shell command for extracting the directory path portion from a path
• Distributed file system – Type of decentralized filesystemPages displaying short descriptions of redirect targets
• Filename – Text string used to uniquely identify a computer file
• Filesystem Hierarchy Standard – Linux standard for directory structure
• Fully qualified file name – Unambiguous name in computer codePages displaying short descriptions of redirect targets
• PATH (variable) – Computer environment variable
• URL – Address on the World Wide Web

• Computer file systems

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