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From: petebob@sequent.UUCP (Pete_Bob Apple)
Newsgroups: comp.sys.sequent
Subject: Re: mv not atomic in dynix
Keywords: mv
Message-ID: <53625@sequent.UUCP>
Date: 20 Feb 91 17:57:30 GMT
References: <1991Feb16.000101.4149@ux1.cso.uiuc.edu> <145463@pyramid.pyramid.com>
Reply-To: petebob@eng3.UUCP (Pete Apple)
Organization: Sequent Computer Systems, Inc.
Lines: 31

In article <145463@pyramid.pyramid.com> csg@pyramid.pyramid.com (Carl S. Gutekunst) writes:
>If you are talking about DYNIX (4.2BSD), this is not true; the rename(2)
>system call is used and it is atomic. Assuming you aren't using the mv(1) in
>the att universe, of course.

The att universe version of mv_dir uses the rename(2) system call.

The ucb universe is just as described, the standard 4.2BSD version of mv(1).

>If you are talking about DYNIX/ptx (SVR3.2), then you are correct. There is
>no rename(2) call, mv(1) is not atomic (it uses link(2) and unlink(2)), and
>you are SOL. That's just the way System V works.

That's not how DYNIX/ptx works.  There is a rename(2) system call in
DYNIX/ptx and mv(1) has been changed to use it.  rename(2) has been
there from the beginning of DYNIX/ptx.  I believe mv(1) was changed to
use rename(2) for the V1.1 release.

[Editorial Comment:  Remember, I'm a just an en-g-neer, not a spokesman:]
One of the ideas behind calling the new operating system DYNIX/ptx was
to give the impression that it is based on the original DYNIX.  Many
important features from DYNIX (such as rename(2)) were added to
DYNIX/ptx while still maintaining industry standards.  (SVR3.2, SVID,
POSIX, XPG, etc)

Personally, I wanted to call it DYNIX_Bob, but no one listened to me.  :-) :-)
-- 
Pete_Bob Apple						Sequent Computer Systems
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Bob is not just a name..				Beaverton, Oregon 97006
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