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89:) was a software subsystem from the early 1980s that could be added to each of a set of interconnected UNIX-like systems to build a distributed system. The latter would be functionally indistinguishable, at both user- and system-level, from a conventional UNIX system. It became a forerunner of
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The term "UNIX United" describes the scheme of combining the overall filesystems of the participating UNIX machines; "Newcastle
Connection" describes the underlying communication layer which enables this. A UNIX United system constructed with the Newcastle Connection is functionally
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In essence, the concept of the "parent directory" was re-interpreted at the root of the filesystem, where it originally had no significant meaning, to mean "this directory is on a remote machine", similar to subsequent
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to the remote machine. All other pathnames would simply go through to the local kernel as usual. (If the current working directory was itself remote, this needed to be taken into account.)
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It did, however, require that all software intended to use it, including shells, the "cp" command, etc. needed to be re-linked with this new library.
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happens as normal on the local system. The second, however, is diverted into the "Newcastle
Connection" software because of the filename's leading "
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root. If the example machine is named "unix1", an overall UNIX United scheme with an additional second machine, "unix2", would look like:
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of its day which was capable of recognising these new semantics. To a first approximation this was to recognise pathnames beginning with
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It required no changes to the UNIX kernel. Rather, it ran in user-space, using a modified version of the
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Continuing one of the previous examples, the "cp" command attempts, as expected, to open the two files:
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network. Subsequent implementations added support for other versions of UNIX (including
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Assuming the command has been relinked with the revised C-library, the first
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indistinguishable from a centralised UNIX system at the system-call level.
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As a reminder, a typical single UNIX directory tree might resemble:
238:( cd /../unix2/home/brian ; cp /../unix1/home/brian/a a )
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317:), network technologies, protocols and hardware architecture (
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97:(NFS). The name derives from the research group at
297:The original implementation at Newcastle was for
465:Catalogue of Distributed File/Operating Systems
215:from "unix1" to "unix2" to sit alongside files
342:Brownbridge, David R.; Marshall, Lindsay F.;
153:UNIX United acts as an extra level above the
8:
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228:cp /home/brian/a /../unix2/home/brian/a
69:Learn how and when to remove this message
223:, example equivalent commands might be:
32:This article includes a list of general
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430:
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463:Borghoff, Uwe M. (6 December 2012).
276:open("/../unix2/home/brian/a", ...)
171:brian (the current directory '.')
38:it lacks sufficient corresponding
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355:Software: Practice and Experience
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510:Network file transfer protocols
136:brian (current directory '.')
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500:Unix network-related software
233:cp a /../unix2/home/brian/a
505:Application layer protocols
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436:"The Newcastle Connection"
348:"The Newcastle Connection"
403:Callaghan, Brent (2000).
305:computers connected by a
515:Distributed file systems
467:. Springer. p. 49.
211:If we wish to copy file
53:more precise citations.
16:UNIX software subsystem
441:. Newcastle University
367:10.1002/spe.4380121206
258:remote procedure calls
105:, which developed it.
495:Network file systems
99:Newcastle University
83:Newcastle Connection
95:Network File System
250:C standard library
384:on 16 August 2016
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361:: 1147–1162.
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103:Brian Randell
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59:December 2018
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443:. Retrieved
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386:. Retrieved
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445:21 December
388:23 December
293:Portability
121:UNIX United
87:UNIX United
51:introducing
489:Categories
329:References
34:references
244:Internals
117:" usage.
346:(1982).
315:System V
101:, under
375:1840438
311:BSD 4.2
299:UNIX V7
47:improve
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303:PDP-11
283:open()
192:brian
186:unix2
165:unix1
36:, but
439:(PDF)
382:(PDF)
371:S2CID
351:(PDF)
254:"/.."
189:home
168:home
133:home
469:ISBN
447:2021
413:ISBN
390:2018
313:and
219:and
162:/..
85:(or
81:The
363:doi
325:).
319:VAX
289:".
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