add customizable shell commands (#16)

shx.el

@@ -85,6 +85,12 @@
  "Triggers of the form: (regexp . function)."
  :type '(alist :key-type regexp :value-type function))
 
+(defcustom shx-customized-shell-commands '()
+ "Map from hostnames/remote identifiers to preferred shells/interpreters.
+Example: ((\"my-host.ca\" . \"/bin/zsh\") (\"^/docker:.*\" . \"/bin/sh\"))"
+ :link '(function-link shx--customized-shell-command)
+ :type '(alist :key-type regexp :value-type string))
+
 (defcustom shx-directory-tracker-regexp nil
  "Input regexp that triggers the `shell-resync-dirs' command."
  :link '(function-link shx--directory-tracker)
@@ -399,7 +405,7 @@ If optional NEW-DIRECTORY is set, use that for `default-directory'."
  (let ((default-directory (or new-directory default-directory)))
  (when (file-remote-p default-directory)
  (message "Restarting shell at %s (C-g to stop)" default-directory))
- (let ((cmd (shx--validate-shell-file-name)))
+ (let ((cmd (shx--shell-command)))
  (shx-insert 'font-lock-doc-face "\n" cmd " at " default-directory "\n")
  ;; manually align comint-file-name-prefix with the default-directory:
  (setq-local comint-file-name-prefix (or (file-remote-p default-directory) ""))
@@ -410,14 +416,30 @@ If optional NEW-DIRECTORY is set, use that for `default-directory'."
  ;; if all that was successful, commit to the new default directory:
  (when new-directory (setq default-directory new-directory)))
 
-(defun shx--validate-shell-file-name ()
- "Guess which shell command to run, even if on a remote host or container."
+(defun shx--shell-command ()
+ "Get the shell command, even if on a remote host or container."
  (declare (side-effect-free t))
- (let ((remote-id (or (file-remote-p default-directory) ""))
- ;; guess which shell command to run per `shell' convention:
- (cmd (or explicit-shell-file-name (getenv "ESHELL") shell-file-name)))
+ (let* ((remote-id (or (file-remote-p default-directory) ""))
+ ;; guess which shell command to run per `shell' convention:
+ (cmd (or explicit-shell-file-name
+ (shx--customized-shell-command remote-id)
+ (getenv "ESHELL")
+ shell-file-name)))
  (cond ((file-exists-p (concat remote-id cmd)) cmd)
- (t (read-file-name "Shell: " nil nil t (concat remote-id "/bin/sh"))))))
+ (t (completing-read "Shell command: " nil)))))
+
+(defun shx--customized-shell-command (host &optional options)
+ "Return user's preferred interpreter for HOST, or nil.
+If OPTIONS is nil, choose from among `shx-customized-shell-commands'."
+ (declare (side-effect-free t))
+ (setq options (or options shx-customized-shell-commands))
+ (when options
+ (let ((regexp (caar options))
+ (interpreter (cdar options))
+ (host (or host "localhost")))
+ (cond
+ ((string-match regexp host) interpreter)
+ ((cdr options) (shx--customized-shell-command host (cdr options)))))))
 
 (defun shx--match-last-line (regexp)
  "Return a form to find REGEXP on the last line of the buffer."
@@ -1019,7 +1041,7 @@ See the function `shx-mode' for details."
  (default-directory (or directory default-directory)))
  ;; `switch-to-buffer' first (`shell' uses the unpredictable `pop-to-buffer')
  (switch-to-buffer name)
- (let ((explicit-shell-file-name (shx--validate-shell-file-name)))
+ (let ((explicit-shell-file-name (shx--shell-command)))
  (shell name))
  ;; shx might already be active due to shx-global-mode:
  (unless shx-mode (shx-mode))))