The Unix designers came from the GE/MIT Multics project, and Multics inspired some Unix features. In particular, Multics has a hierarchical filesystem, and so does Unix.
On Multics, pathnames were of the form:
but Unix uses
Is there any documentation of why they chose that syntax instead of copying Multics?
I thought of this because
> has become common in modern day displays of other hierarchical paths, such as breadcrumb lists in web applications and CSS child selectors.
Multics also used
< to represent upward motion in relative pathnames, e.g. Unix
This has a nice symmetry that
../ lacks, although
.. has the advantage of being implemented in the filesystem itself (it's simply a link to the parent directory). On Multics,
< is implemented in a user-mode library that canonicalizes pathnames before being passed to the kernel.