Path: utzoo!attcan!uunet!usenix!jsq From: fouts@bozeman.bozeman.ingr (Martin Fouts) Newsgroups: comp.std.unix Subject: Re: Standards Update, IEEE 1003.4: Real-time Extensions Message-ID: <523@usenix.ORG> Date: 17 Sep 90 21:02:49 GMT References: <448@usenix.ORG> <457@usenix.ORG> <488@usenix.ORG> <495@usenix.ORG> Sender: jsq@usenix.ORG Organization: INTERGRAPH (APD) -- Palo Alto, CA Lines: 84 Approved: jsq@usenix.org (Moderator, John Quarterman) X-Submissions: std-unix@uunet.uu.net Submitted-by: fouts@bozeman.bozeman.ingr (Martin Fouts) >>>>> On 7 Sep 90 15:23:19 GMT, chip@tct.uucp (Chip Salzenberg) said: Chip> According to fouts@bozeman.bozeman.ingr (Martin Fouts): >I'm not sure which Unix you've been running for the past five or more >years, but a lot of stuff doesn't live in the file system name space ... Chip> The absense of sockets (except UNIX domain), System V IPC, etc. from Chip> the file system is, in the opinion of many, a bug. It is a result of Chip> Unix being extended by people who do not understand Unix. ^-------------------------------^ My aren't we superior. (;-) At one time, I believed that sockets belonged in the filesystem name space. I spent a long time arguing this point with members of the networking community before they convinced me that certain transient objects do not belong in that name space. (See below) Chip> Research Unix, which is the result of continued development by the Chip> creators of Unix, did not take things out of the filesystem. To the Chip> contrary, it put *more* things there, including processes (via the Chip> /proc pseudo-directory). The value of proc in the file system are debatable. Certain debugging tools are easier to hang on an fcntl certain others are not. However, the presences of the proc file system is not a strong arguement for the inclusion of othere features in the file system. Chip> It is true that other operating systems get along without devices, Chip> IPC, etc. in their filesystems. That's fine for them; but it's not Chip> relevant to Unix. Unix programming has a history of relying on the Chip> filesystem to take care of things that other systems handle as special Chip> cases -- devices, for example. The idea that devices can be files but Chip> TCP/IP sockets cannot runs counter to all Unix experience. Unix programming has a history of using the filesystem for some things and not using it for others. For example, I can demonstrate a semantic under which it is possible to put the time of day clock into the file system and reference it by opening the i.e. /dev/timeofday file. Each time I read from that file, I would get the current time. Via fcntls, I could extend this to handle timer functions. It wasn't done in Unix. (I've done similar things in other OSs I've designed, though.) The whole point of the response which you partially quoted was to remind the poster I was responding to that not all functions which might have been placed in the filesystem automatically have. Chip> The reason why I continue this discussion here, in comp.std.unix, is Chip> that many Unix programmers hope that the people in the standardization Chip> committees have learned from the out-of-filesystem mistake, and will Chip> rectify it. Chip> -- The reason I respond is that it is not automatically safe to assume that something belongs in the file system because something else is already there. There is also an explicit problem not mentioned in this discussion which is the distinction between filesystem name space and filesystem semantics. Sometimes there are objects which would be reasonable to treat with filesystem semantics for which there is no reasonable mechanism for introducing them into the filesystem name space. Because of the way network connections are made, I have been convinced by networking experts (who are familiar with the "Unix style") that the filesystem namespace does not have a good semantic match for the network name space. Chip> Chip Salzenberg at Teltronics/TCT , Chip> Volume-Number: Volume 21, Number 89 Marty -- Martin Fouts UUCP: ...!pyramid!garth!fouts (or) uunet!ingr!apd!fouts ARPA: apd!fouts@ingr.com PHONE: (415) 852-2310 FAX: (415) 856-9224 MAIL: 2400 Geng Road, Palo Alto, CA, 94303 Moving to Montana; Goin' to be a Dental Floss Tycoon. - Frank Zappa Volume-Number: Volume 21, Number 114