This post is part of a series about shells in Emacs:

Remote interactive shells

In a previous post we dealt with spawning interactive shells.

In it, we defined a new function friendly-shell, an objectively clearer version of shell.

It can be used to easilly define commands for spawning local and remote shells with an arbitrary shell interpreter.

But it can be quite cumbersome to have to define a command for each and every remote connection.

Ideally we’d want a command that prompts for a remote path and spawn a shell there.

Prompting for a remote path

The remote path format understood by Emacs looks like this:

/<method>:[<user>[%<domain>]@]<host>[%<port>][:<localname>]

The /<method>: prefix is mandatory, required for Emacs to detect that the path is remote.

<method> can have a default value (configured with tramp-default-method and tramp-default-method-alist) but the user still need to type in the prefix /-: to use it.

In the context of a command explicitely prompting for a remote path, it’s quite cumbersome for the user to have to type in this /<method>: prefix.

We want a light wrapper that also supports this more permissive format:

[<user>[%<domain>]@]<host>[%<port>][:<localname>]

That wrapper is function friendly-tramp-path-dissect provided by package friendly-tramp-path.

Default remote interpreter configuration

Introduced in Emacs 26.2, connection-local vars allow to have a per host interpreter configuration.

Package friendly-shell comes with its own, more versatile, implementation of connection-local vars.

Both options are explained in details in post: Emacs shell interpreter configuration.

Putting it all together

(require 'friendly-tramp-path)
(require 'with-shell-interpreter)
(require 'prf-shell)

(cl-defun friendly-remote-shell (&key path
                                      interpreter interpreter-args
                                      command-switch
                                      w32-arg-quote)
  (interactive)
  (let* ((path (or path (read-string "Host: ")))
         (path (with-shell-interpreter--normalize-path path))
         (vec (friendly-tramp-path-dissect path))
         (path (tramp-make-tramp-file-name (tramp-file-name-method vec)
                                           (tramp-file-name-user vec) (tramp-file-name-domain vec)
                                           (tramp-file-name-host vec) (tramp-file-name-port vec)
                                           (tramp-file-name-localname vec))))
    (friendly-shell :path path
                    :interpreter interpreter
                    :interpreter-args interpreter-args
                    :command-switch command-switch
                    :w32-arg-quote w32-arg-quote)))

And voilà! Now to connect to a remote server we just has to type:

M-x friendly-remote-shell <RET>
pi@raspberry <RET>

The code for friendly-remote-shell can be found in package friendly-remote-shell.


Tagged #emacs.