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.