* eshell/esh-ext.el (eshell-external-command): Pass args to

`eshell-find-interpreter'.
(eshell-find-interpreter): Add new second parameter ARGS.

* eshell/em-script.el (eshell-script-initialize): Add second arg
to the function added as MATCH to `eshell-interpreter-alist'

* eshell/em-dirs.el (eshell-dirs-initialize): Add second arg to
the function added as MATCH to `eshell-interpreter-alist'

* eshell/em-term.el (eshell-visual-subcommands): New defcustom.
(eshell-visual-options): New defcustom.
(eshell-escape-control-x): Adapt docstring.
(eshell-term-initialize): Test `eshell-visual-subcommands' and
`eshell-visual-options' in addition to `eshell-visual-commands'.
(eshell-exec-visual): Pass args to `eshell-find-interpreter'.

lisp/eshell/em-dirs.el

@@ -207,7 +207,8 @@ Thus, this does not include the current directory.")
   (when eshell-cd-on-directory
     (make-local-variable 'eshell-interpreter-alist)
     (setq eshell-interpreter-alist
-	  (cons (cons 'eshell-lone-directory-p
+	  (cons (cons (lambda (file args)
+			(eshell-lone-directory-p file))
 		      'eshell-dirs-substitute-cd)
 		eshell-interpreter-alist)))
 

lisp/eshell/em-script.el

@@ -61,7 +61,7 @@ This includes when running `eshell-command'."
   "Initialize the script parsing code."
   (make-local-variable 'eshell-interpreter-alist)
   (setq eshell-interpreter-alist
-	(cons '((lambda (file)
+	(cons '((lambda (file args)
 		  (string= (file-name-nondirectory file)
 			   "eshell")) . eshell/source)
 	      eshell-interpreter-alist))

lisp/eshell/em-term.el

@@ -65,6 +65,39 @@ which commands are considered visual in nature."
   :type '(repeat string)
   :group 'eshell-term)
 
+(defcustom eshell-visual-subcommands
+  nil
+  "An alist of the form
+
+  ((COMMAND1 SUBCOMMAND1 SUBCOMMAND2...)
+   (COMMAND2 SUBCOMMAND1 ...))
+
+of commands with subcommands that present their output in a
+visual fashion.  A likely entry is
+
+  (\"git\" \"log\" \"diff\" \"show\")
+
+because git shows logs and diffs using a pager by default."
+  :type '(repeat (cons (string :tag "Command")
+		       (repeat (string :tag "Subcommand")))))
+
+(defcustom eshell-visual-options
+  nil
+  "An alist of the form
+
+  ((COMMAND1 OPTION1 OPTION2...)
+   (COMMAND2 OPTION1 ...))
+
+of commands with options that present their output in a visual
+fashion.  For example, a sensible entry would be
+
+  (\"git\" \"--help\")
+
+because \"git <command> --help\" shows the command's
+documentation with a pager."
+  :type '(repeat (cons (string :tag "Command")
+		       (repeat (string :tag "Option")))))
+
 ;; If you change this from term-term-name, you need to ensure that the
 ;; value you choose exists in the system's terminfo database.  (Bug#12485)
 (defcustom eshell-term-name term-term-name
@@ -77,8 +110,10 @@ used."
 
 (defcustom eshell-escape-control-x t
   "If non-nil, allow <C-x> to be handled by Emacs key in visual buffers.
-See the variable `eshell-visual-commands'.  If this variable is set to
-nil, <C-x> will send that control character to the invoked process."
+See the variables `eshell-visual-commands',
+`eshell-visual-subcommands', and `eshell-visual-options'.  If
+this variable is set to nil, <C-x> will send that control
+character to the invoked process."
   :type 'boolean
   :group 'eshell-term)
 
@@ -93,9 +128,14 @@ nil, <C-x> will send that control character to the invoked process."
   (make-local-variable 'eshell-interpreter-alist)
   (setq eshell-interpreter-alist
 	(cons (cons (function
-		     (lambda (command)
-		       (member (file-name-nondirectory command)
-			       eshell-visual-commands)))
+		     (lambda (command args)
+		       (let ((command (file-name-nondirectory command)))
+			 (or (member command eshell-visual-commands)
+			     (member (car args)
+				     (cdr (assoc command eshell-visual-subcommands)))
+			     (intersection args
+					   (cdr (assoc command eshell-visual-options))
+					   :test 'string=)))))
 		    'eshell-exec-visual)
 	      eshell-interpreter-alist)))
 
@@ -104,7 +144,7 @@ nil, <C-x> will send that control character to the invoked process."
 ARGS are passed to the program.  At the moment, no piping of input is
 allowed."
   (let* (eshell-interpreter-alist
-	 (interp (eshell-find-interpreter (car args)))
+	 (interp (eshell-find-interpreter (car args) (cdr args)))
 	 (program (car interp))
 	 (args (eshell-flatten-list
 		(eshell-stringify-list (append (cdr interp)

lisp/eshell/esh-ext.el

@@ -125,9 +125,10 @@ Each member is a cons cell of the form:
 
   (MATCH . INTERPRETER)
 
-MATCH should be a regexp, which is matched against the command name,
-or a function.  If either returns a non-nil value, then INTERPRETER
-will be used for that command.
+MATCH should be a regexp, which is matched against the command
+name, or a function of arity 2 receiving the COMMAND and its
+ARGS (a list).  If either returns a non-nil value, then
+INTERPRETER will be used for that command.
 
 If INTERPRETER is a string, it will be called as the command name,
 with the original command name passed as the first argument, with all
@@ -215,6 +216,7 @@ causing the user to wonder if anything's really going on..."
   (setq args (eshell-stringify-list (eshell-flatten-list args)))
   (let ((interp (eshell-find-interpreter
 		 command
+		 args
 		 ;; `eshell-find-interpreter' does not work correctly
 		 ;; for Tramp file name syntax.  But we don't need to
 		 ;; know the interpreter in that case, therefore the
@@ -267,7 +269,7 @@ Return nil, or a list of the form:
 		(list (match-string 1)
 		      file)))))))
 
-(defun eshell-find-interpreter (file &optional no-examine-p)
+(defun eshell-find-interpreter (file args &optional no-examine-p)
   "Find the command interpreter with which to execute FILE.
 If NO-EXAMINE-P is non-nil, FILE will not be inspected for a script
 line of the form #!<interp>."
@@ -277,8 +279,9 @@ line of the form #!<interp>."
 	    (dolist (possible eshell-interpreter-alist)
 	      (cond
 	       ((functionp (car possible))
-		(and (funcall (car possible) file)
-		     (throw 'found (cdr possible))))
+		(let ((fn (car possible)))
+		  (and (funcall fn file args)
+		       (throw 'found (cdr possible)))))
 	       ((stringp (car possible))
 		(and (string-match (car possible) file)
 		     (throw 'found (cdr possible))))
@@ -312,7 +315,7 @@ line of the form #!<interp>."
 	    (setq interp (eshell-script-interpreter fullname))
 	    (if interp
 		(setq interp
-		      (cons (car (eshell-find-interpreter (car interp) t))
+		      (cons (car (eshell-find-interpreter (car interp) args t))
 			    (cdr interp)))))
 	  (or interp (list fullname)))))))