[COFF] Re: [TUHS] Re: Be there a "remote diff" utility?

[John Cowan <cowan@ccil.org>]

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The Newcastle Connection, aka Unix United, was an early experiment in
transparent networking: see <
https://web.archive.org/web/20160816184205/http://www.cs.ncl.ac.uk/research/pubs/articles/papers/399.pdf>
for a high-level description.  A name of the form "/../host/path"
represented a file or device on a remote host in a fully transparent way.
This was layered on V7 at the libc level, so that the kernel did not need
to be modified (though the shell did, since it was not libc-based at the
time).  MUNIX was an implementation of the same idea using System V as the
underlying system.

This appears to be a VHS vs. Betamax battle: NFS was not transparent, but
Sun had far more marketing clout.  However, the Manchester Connection
required a single uid space (as far as I can tell), which may also have
been a (perceived) institutional barrier.

On Thu, May 16, 2024 at 3:34 AM Ralph Corderoy <ralph@inputplus.co.uk>
wrote:

> Hi,
>
> I've set ‘mail-followup-to: coff@tuhs.org’.
>
> > > Every so often I want to compare files on remote machines, but all
> > > I can do is to fetch them first (usually into /tmp); I'd like to do
> > > something like:
> > >
> > >     rdiff host1:file1 host2:file2
> > >
> > > Breathes there such a beast?
>
> No, nor should there.  It would be slain less it beget rcmp, rcomm,
> rpaste, ...
>
> > > Think of it as an extension to the Unix philosophy of "Everything
> > > looks like a file"...
>
> Then make remote files look local as far as their access is concerned.
> Ideally at the system-call level.  Less ideal, at libc.a.
>
> > Maybe
> >
> >     diff -u <(ssh host1 cat file1) <(ssh host2 cat file2)
>
> This is annoyingly noisy if the remote SSH server has sshd_config(5)'s
> ‘Banner’ set which spews the contents of a file before authentication,
> e.g. the pointless
>
>     This computer system is the property of ...
>
>     Disconnect NOW if you have not been expressly authorised to use this
>     system.  Unauthorised use is a criminal offence under the Computer
>     Misuse Act 1990.
>
>     Communications on or through ...uk's computer systems may be
>     monitored or recorded to secure effective system operation and for
>     other lawful purposes.
>
> It appears on stderr so doesn't upset the diff but does clutter.
> And discarding stderr is too sloppy.
>
> --
> Cheers, Ralph.
>

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