bug#70792: 30.0.50; [PATCH] Add Eshell support for expanding absolute file names within the current remote connection

[Jim Porter]

One oddity of Eshell is that even when you're connected to a remote host 
(usually you just "cd" into a remote directory using Tramp syntax), 
absolute file names are still on your *local* host when running any Lisp 
commands. However, running *external* commands (programs on the remote 
host), absolute file names are on that remote host.

When you think about how it's implemented, this makes sense: Lisp 
commands always run in the local Emacs process, but external programs 
run on the remote. So naturally, "absolute" file names are relative to a 
different host in either case. This wouldn't be so bad except that it's 
not always obvious when you're running a Lisp command or not. Eshell 
provides Lisp implementations of some common commands, like "cat", but 
it also transparently falls back to the external program if it doesn't 
understand some option. This results in it being pretty hard to tell 
what's going to happen when you run a command.

There's an "elecslash" module for Eshell that helps with this, but it 
can't tell when you have a Lisp command that will actually fallback to 
the external program when you run it.

Instead, the attached patch provides a new way to handle this: if you 
enable 'eshell-connection-local-file-names', then "normal" absolute file 
names like "/foo/bar" or "~/user" are evaluated relative to the current 
remote connection (if any). Eshell does this by expanding the file name 
to a full remote name like "/ssh:remote:/foo/bar". If these strings get 
sent to an external program, Eshell will unexpand them back to a 
host-local name (it will make sure that the remote host is correct, too).

You can also keep Eshell from performing this expansion on a 
case-by-case basis by quoting the file name (like "this", 'this', or 
/:this) or escaping the leading / or ~.

0001-Mark-all-backslash-escaped-characters-in-Eshell-as-e.patch
Description: Text document

0002-Let-Eshell-expand-absolute-file-names-via-the-curren.patch
Description: Text document