splitext

Splitext is a function in Python’s standard library for path manipulation, most commonly accessed as os.path.splitext. It splits a pathname into a pair (root, ext). The root is the portion of the path without the final extension, and ext is the extension including the leading dot, or an empty string if there is no extension. The split operates on the final path component, leaving the preceding directories unchanged. The function does not access the filesystem; it analyzes the string itself.

How it determines the split: splitext looks for the last dot in the final path component. If the final component begins with a dot and has no other dots (as in hidden Unix files like .bashrc), it is treated as having no extension. For example, splitext("archive.tar.gz") yields ("archive.tar", ".gz"), while splitext("/path/to/file") yields ("/path/to/file", "").

Common usage is to obtain or modify the filename’s extension, validate file types, or construct new names. It is especially useful in workflows that need to distinguish between a base name and its type without reading the file contents.

Platform considerations: The behavior is provided by platform-specific implementations (posixpath.splitext on POSIX systems and ntpath.splitext on Windows). In practice, os.path.splitext delegates to the appropriate module based on the running platform, and this affects how drive letters and path separators are handled.

Limitations: splitext does not check for file existence or content; it operates purely on the path string. For complex naming schemes or unusual extensions, additional logic may be required.