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    This is far more than I ever expected. Thank you, and extra thanks for the further reading! Commented Dec 27, 2017 at 9:27
  • doc.cat-v.org/plan_9/4th_edition/papers/lexnames talks about some of the problems with .. in the context of Plan9, Commented Dec 27, 2017 at 16:12
  • @JdeBP: Perhaps I’m missing something.  You say, “Internally, within …, bash, … and …, the shell additionally keeps track of the working directory using string manipulation of an internal string variable.  …, it adjusts the string to remove . and .. components and to chase down symbolic links replacing them with their linked-to names. …  The name in the internal string variable is tracked by a shell variable named PWD …” (emphasis added).  … (Cont’d) Commented Mar 8, 2018 at 8:18
  • (Cont’d) … But your example shows PWD = …/b after a cd b command, even though b is a symbolic link to a — so the shell doesn’t “chase down” the a -> b link. Did you misstate, or did I misread? Commented Mar 8, 2018 at 8:18
  • I simply glossed over a side point, and pointed you to the code for details. See the various shells' manuals for when and how they decide to chase symbolic links or not. The Z shell handily calls its shell option that is one part of the decision formula, CHASE_LINKS. Commented Mar 8, 2018 at 8:40