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[2603:6010:dc07:54e3:fd1b:d90b:68a7:af5c]) by smtp.gmail.com with ESMTPSA id f7sm16894010qkh.45.2021.02.09.11.06.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Feb 2021 11:06:27 -0800 (PST) To: John Cowan , "Theodore Ts'o" References: From: Chet Ramey Organization: ITS, Case Western Reserve University Message-ID: Date: Tue, 9 Feb 2021 14:06:25 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Mirapoint-IP-Reputation: reputation=Good-1, source=Queried, refid=tid=0001.0A742F90.6022D67F.0009, actions=tag X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A742F17.6022DD34.0076, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2016-11-06 16:00:04, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: dda8b01a42c3cda59e742af0fddb9879 X-Mirapoint-IP-Reputation: reputation=good-1, source=Fixed, refid=n/a, actions=tag X-Junkmail-Status: score=8/80, host=mpv2-2015.case.edu X-Junkmail-PrAS-Raw: score=8/80, refid=2.7.2:2021.2.9.175717:17:8.317, ip=, rules=__YOUTUBE_RCVD, DKIM_SIGNATURE, __X_GOOGLE_DKIM_SIGNATURE, __HAS_REPLYTO, __HAS_CC_HDR, __MULTIPLE_RCPTS_CC_X2, __CC_NAME, __CC_NAME_DIFF_FROM_ACC, __SUBJ_REPLY, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __TO_MALFORMED_2, __MULTIPLE_RCPTS_TO_X2, __TO_NAME, __TO_NAME_DIFF_FROM_ACC, __HAS_REFERENCES, __REFERENCES, __HAS_FROM, FROM_EDU_TLD, __HAS_MSGID, __SANE_MSGID, DATE_TZ_NA, __USER_AGENT, __MOZILLA_USER_AGENT, __MIME_VERSION, __IN_REP_TO, __CT, __CT_TEXT_PLAIN, __CTE, __REPLYTO_SAMEAS_FROM_ADDY, __REPLYTO_SAMEAS_FROM_ACC, __FROM_DOMAIN_IN_ANY_CC2, __RCPT_DOMAIN_NOT_TO, __REPLYTO_SAMEAS_FROM_DOMAIN, __DKIM_ALIGNS_1, __DKIM_ALIGNS_2, __ANY_URI, __URI_MAILTO, __URI_WITH_PATH, __URI_ENDS_IN_SLASH, __URI_NO_WWW, __CP_URI_IN_BODY, __SUBJ_ALPHA_NEGATE, __URI_IN_BODY, __URI_NOT_IMG, __MAIL_CHAIN, __FORWARDED_MSG, __BODY_NO_MAILTO, __NO_HTML_TAG_RAW, [TRUNCATED], so=2010-03-03 19:42:08, dmn=2016-08-03-0138 Subject: Re: [TUHS] Macs and future unix derivatives X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: chet.ramey@case.edu Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 2/9/21 12:31 PM, John Cowan wrote: > From BTSJ 57:6: > > The file system maintains no locks visible to the user, nor is there > any restriction on the number of users who may have a file open for > reading or writing. Although it is possible for the contents of a file > to become scrambled when two users write on it simultaneously, in > practice difficulties do not arise.We take the view that locks are > neither necessary nor sufficient, in our environment, to prevent > interference between users of the same file. They are unnecessary > because we are not faced with large, single-file databases maintained > by independent processes. They are insufficient because locks in the > ordinary sense, whereby one user is prevented from writing on a file > that another user is reading, cannot prevent confusion when, for > example, both users are editing a file with an editor that makes a copy > of the file being edited. "In our environment" is doing some pretty heavy lifting there. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/