To add to Ron's post, Plan 9's cpu exports the origination's namespace to the destination; by convention it is mounted on /mnt/term at destination.

host1% cpu -h host2

host2% diff file2 /mnt/term/usr/me/file1

On Thu, May 16, 2024 at 10:09 AM ron minnich <rminnich@gmail.com> wrote:

" The 9import tool allows an arbitrary file on a remote system, with the capability of running the Plan 9 exportfs(4) service, to be imported into the local name space. Usually file is a directory, so the complete file tree under the directory is made available."

https://9fans.github.io/plan9port/man/man4/9import.html

9import host1 / /tmp/host1

9import host2 /tmp/host2

diff /tmp/host1/a/b/c /tmp/host2/a/b/c

(or whatever command you want that works with files. No need for stuff like 'rdiff' etc.)

stuff you take for granted on some systems ...

I have the plan 9 cpu command working (written in Go) and I think it's time I get import working more widely, it's just too useful. 

On Thu, May 16, 2024 at 2:01 AM <arnold@skeeve.com> wrote:

Ralph Corderoy <ralph@inputplus.co.uk> wrote:

> > 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
>
> [....]
>
> It appears on stderr so doesn't upset the diff but does clutter.

All true, I didn't think about that.

> And discarding stderr is too sloppy.

But the author of a personal script knows his/her remote machines
and can decide if

     diff -u <(ssh host1 cat file1 2>/dev/null) <(ssh host2 cat file2 2>/dev/null)

is appropriate or not.

My main point was that the problem is easily solved with a
few lines of shell, so no need for a utility, especially one
written in C or some other compiled language.

Thanks,

Arnold