joinpath

Joinpath is a function or method used in several programming environments to build a filesystem path by concatenating a base path with one or more path components. It automatically inserts the correct directory separators for the host operating system and handles normalization to avoid issues from manual string concatenation. Most implementations support a base path followed by multiple segments and return a path string or path object representing the combined path.

In Julia, joinpath is found in the Base.Filesystem module. It is variadic, taking a base path and any number of additional components: joinpath(base, seg1, seg2, ...). If any segment is an absolute path, earlier components are discarded and the result starts from that absolute path. The function also normalizes redundant separators and dot segments where supported.

Python’s pathlib module exposes Path.joinpath, a method on Path objects. Path('/usr').joinpath('local','bin') yields '/usr/local/bin' on POSIX systems or the corresponding path on Windows. Like Julia, an absolute argument resets the base in many cases.

Other environments offer similar functionality under the same or similar names. For example, PowerShell provides the Join-Path cmdlet to combine a base path and a child path, returning a normalized path appropriate to the provider. In many languages the concept is essential for cross-platform scripts and applications that manipulate file systems.