Warren is right that even the First Edition manual says that init mounts /usr, implying that /usr was a distinct file system even that early. It seems to me that the original question Greg forwarded from the NetBSD list was also after when /usr/bin appeared, which isn't necessarily the same date. A possible answer from old manuals: - Second Edition sh(I) (dated 3/15/72): If the first argument is the name of an executable file, it is invoked; otherwise the string "/bin/" is prepended to the argument. (In this way the standard commands, which reside in "/bin", are found.) If the "/bin" file exists, but is not executable, it is used by the shell as a command file. - Third Edition sh(I) (dated 1/15/73): If the first argument is the name of an executable file, it is invoked; otherwise the string "/bin/" is prepended to the argument. (In this way most standard commands, which reside in "/bin", are found.) If no such command is found, the string "/usr" is further prepended (to give "/usr/bin/command") and another attempt is made to execute the resulting file. (Certain "overflow" commands live in "/usr/bin".) If the "/usr/bin" file exists, but is not executable, it is used by the shell as a command file. Notice the odd detail that non-executable files in /bin (early on) or /usr/bin (later) get special treatment. Does this mean that shell scripts that weren't in /usr/bin had to be invoked explicitly via `sh script' instead of just `script'? Even deeper historic trivia: it occurred to me to check the fragments of the PDP-7 system I have on paper to see whether /usr existed then. I was quickly reminded that it almost certainly didn't because subdirectories weren't really used then; there were no pathnames in that system. (You could open only files in the working directory, though you could link from another directory.) When asked to invoke `x', the shell first tried to open `x', then to link `x' from directory `system' and open the result. (Presumably it remembered to remove the needless link after the open, but I'm not quite certain; the old paper copy is missing a few lines just there.) So even the name `bin' doesn't date back quite to the beginning. Norman Wilson Received: (from major@localhost) by minnie.cs.adfa.edu.au (8.9.3/8.9.3) id KAA39649 for pups-liszt; Tue, 18 Apr 2000 10:10:53 +1000 (EST) Received: from henry.cs.adfa.edu.au (henry.cs.adfa.edu.au [131.236.21.158]) by minnie.cs.adfa.edu.au (8.9.3/8.9.3) with ESMTP id KAA39645 for <pups(a)minnie.cs.adfa.edu.au>au>; Tue, 18 Apr 2000 10:10:42 +1000 (EST) Received: (from wkt@localhost) by henry.cs.adfa.edu.au (8.9.2/8.9.3) id KAA42226 for pups(a)minnie.cs.adfa.edu.au; Tue, 18 Apr 2000 10:10:41 +1000 (EST) (envelope-from wkt) From: Warren Toomey <wkt(a)cs.adfa.edu.au> Message-Id: <200004180010.KAA42226(a)henry.cs.adfa.edu.au> Subject: Re: Early file system layouts In-Reply-To: <200004172217.IAA38973(a)minnie.cs.adfa.edu.au> from "norman(a)nose.cs.utoronto.ca" at "Apr 16, 2000 2:43:14 pm" To: Date: Tue, 18 Apr 2000 10:10:41 +1000 (EST) Cc: pups(a)minnie.cs.adfa.edu.au Reply-To: wkt(a)cs.adfa.edu.au X-Mailer: ELM [version 2.4ME+ PL43 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-pups(a)minnie.cs.adfa.edu.au Precedence: bulk In article by norman(a)nose.cs.utoronto.ca: Can't tell, we don't have the source code. In the Nsys kernel (dated just before the 4th Edition), files must have the execute bit on or they can't be exec(2)d. Warren