uiop:parse-unix-namestring

(uiop:parse-unix-namestring name &key type defaults dot-dot ensure-directory &allow-other-keys)

Coerces name into a pathname using Unix syntax -- UIOP's portable pathname reader. A pathname passes through, nil stays nil, a symbol is downcased and read as a string. Empty and "." directory components are dropped; ".." is kept as one level up. :type a string makes the whole last component the NAME with that type; :ensure-directory (or :type :directory) forces directory form. Remaining keys go to uiop:ensure-pathname (so :want-relative t rejects an absolute string).

Backend support

Works on all four backends (Lisp source, uiop-pathname.lisp).