The DEC operating systems (eg. RSX with its MCR shell and VMS with its DCL shell) also handled command-line switches this way (eg. PIP/LIST to list files in a d

The DEC operating systems (eg. RSX with its MCR shell and VMS with its DCL shell) also handled command-line switches this way (eg. PIP/LIST to list files in a directory). Of course, they didn't use unixy paths for directories. A fully-qualified file name would be something like (and it's been decades so if I get it wrong forgive me) DRA0:[SYS.USERS.BREGMA.PROJECT.SOURCES]HELLO.C;1 and anyone who was sane would use logical names in DCL to make things readable.