Expanduser

Expanduser is a function in Python's standard library that expands a leading tilde (~) in a path to a user’s home directory. It is available as os.path.expanduser(path) and, in the pathlib API, as Path.expanduser().

How it works: If the path begins with ~ or ~user, the function resolves that user’s home directory. For the current user, it uses the system’s notion of the home directory; for a named user, it queries the system user database (for example, the passwd database on Unix-like systems). If the home directory cannot be determined, or the requested user does not exist, the function typically leaves the path unchanged.

On Unix-like systems, expansions map ~ to the value of the HOME variable or the home directory of the current user, and ~user to that user’s directory as found in the system database. On Windows, expansion uses environment variables such as USERPROFILE or HOME, and may reference the user’s profile directory.

Use cases: It helps write portable code that reads or writes user-specific files without assuming fixed paths. It is distinct from shell tilde expansion, which occurs in interactive shells rather than within Python code.

Examples: os.path.expanduser("~/docs") might yield /home/username/docs on Unix or C:\Users\username\docs on Windows. Path("/path").expanduser() behaves similarly, returning a new Path object.