Working With the Universal Naming Convention (UNC Path)

The Universal Naming Convention is the naming system used in Microsoft Windows for accessing shared network folders and printers on a local area network.

Support for working with UNC paths in Unix and other operating systems use cross-platform file sharing technologies like Samba.

UNC Name Syntax

UNC names identify network resources using a specific notation. These names consist of three parts: a host device name, a share name, and an optional file path.

These three elements are combined using backslashes:

\\host-name\share-name\file_path

The Host-Name Section

The host-name portion of a UNC name can consist of either a network name string set by an administrator and maintained by a network naming service like DNS or WINS, or by an IP address.

These hostnames normally refer to either a Windows PC or a Windows-compatible printer.

The Share-Name Section

The share-name portion of a UNC pathname references a label created by an administrator or, in some cases, within the operating system.

In most versions of Microsoft Windows, the built-in share name admin$ refers to the root directory of the operating system installation—usually C:\Windows but sometimes C:\\WINDOWS.

UNC paths do not include Windows driver letters, only a label that may reference a particular drive.

The File_Path Section

The file_path portion of a UNC name references a local subdirectory beneath the share section. This part of the path is optional.

When no file_path is specified, the UNC path simply points to the top-level folder of the share.

The file_path must be absolute. Relative paths are not allowed.

How to Work With UNC Paths

Consider a standard Windows PC or Windows-compatible printer named Teela. In addition to the built-in admin$ share, say you have also defined a share point called temp that is located at C:\temp.

Using UNC names, this is how you would connect to folders on Teela.

\\teela\admin$ (to reach C:\WINNT)
\\teela\admin$\system32 (to reach C:\WINNT\system32)
\\teela\temp (to reach C:\temp)

New UNC shares can be created through Windows Explorer. Just right-click a folder and choose one of the Share menu options to assign it a share name.

What About Other Backslashes in Windows?

Microsoft uses other backslashes throughout Windows, such as in the local file system. One example is C:\Users\Administrator\Downloads to show the path to the Downloads folder in the Administrator user account.

You might also see backslashes when working with command-line commands.

Alternatives to UNC

Using Windows Explorer or the Command Prompt or Windows PowerShell, and with proper security credentials, you can map network drives and remotely access folders on a computer using its drive letter rather than a UNC path

Microsoft established UNC for Windows after Unix systems had defined a different pathname convention. Unix network paths (including Unix and Linux related operating systems like macOS and Android) use forward slashes instead of backslashes.