diff --git a/ciel.asd b/ciel.asd
index 7e68cb6..312557f 100644
--- a/ciel.asd
+++ b/ciel.asd
@@ -85,6 +85,7 @@
                :cl-punch
 
                :serapeum
+               :shlex
 
                ;; tests
                :fiveam
@@ -111,6 +112,7 @@
                         ((:file "ciel")
                          ))
                (:file "repl")
+               (:file "shell-utils")
                (:file "repl-utils"))
 
   :build-operation "program-op"
diff --git a/docs/repl.md b/docs/repl.md
index 3299bca..3ee2f82 100644
--- a/docs/repl.md
+++ b/docs/repl.md
@@ -63,19 +63,31 @@ Use square brackets `[...]` to write a shell script, and use `$` inside it to es
 
 The result is concatenated into a string and printed on stdout.
 
-This feature is only available in CIEL's REPL, not on the CIEL-USER package.
+This feature is only available by default in CIEL's REPL, not on the
+CIEL-USER package. To enable it yourself, do:
 
-Some programs are **visual** / interactive / ncurses-based, and need
+      (ciel:enable-shell-passthrough)
+
+But, some programs are **visual**, or interactive, because they have an ncurses or similar interface. They need
 to be run in their own terminal window. CIEL recognizes a few (`vim`,
-`htop`, `man`…) and runs them in the first terminal emulator found on
-the system of `terminator`, `xterm`, `gnome-terminal`). See the
-`*visual-commands*` variable.
+`htop`, `man`… see `*visual-commands*`) and runs them in the first terminal emulator found on
+the system: `terminator`, `xterm`, `gnome-terminal`, Emacs' `vterm` (with emacsclient) or your own.
+
+So, you can run a command similar to this one:
+
+    ENV=env sudo htop
+
+and it will open in a new terminal (hint: a visual command doesn't require the `!` prefix).
+
+To use your terminal emulator of choice, do:
+
+    (push "myterminal" *visual-terminal-emulator-choices*)
 
 > Note: this feature is experimental.
 
 > Note: we encourage our users to use Emacs rather than a terminal!
 
-We use the [Clesh](https://github.com/Neronus/clesh) library.
+We use the [Clesh](https://github.com/Neronus/clesh) library for the `!` shell passthrough.
 
 See also [SHCL](https://github.com/bradleyjensen/shcl) for a more unholy union of posix-shell and Common Lisp.
 
diff --git a/repl-utils.lisp b/repl-utils.lisp
index a6af89a..4d08698 100644
--- a/repl-utils.lisp
+++ b/repl-utils.lisp
@@ -47,49 +47,3 @@ bar:qux
       (format t "~c[1C" #\esc))
     (finish-output)))
 
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; Run visual / interactive / ncurses commands in their terminal window.
-;;;
-;;; How to guess a program is interactive?
-;;; We currently look from a hand-made list (à la Eshell).
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-
-(defparameter *visual-commands*
-  '(;; "emacs -nw" ;; in eshell, concept of visual-subcommands.
-    "vim" "vi"
-    "nano"
-    "htop" "top"
-    "man" "less" "more"
-    "screen" "tmux"
-    "lynx" "links" "mutt" "pine" "tin" "elm" "ncftp" "ncdu"
-    "ranger"
-    ;; last but not least
-    "ciel-repl")
-  "List of visual/interactive/ncurses-based programs that will be run in their own terminal window.")
-
-(defparameter *visual-terminal-emulator-choices*
-  '("terminator" "x-terminal-emulator" "xterm" "gnome-terminal"))
-
-(defparameter *visual-terminal-switches* '("-e")
-  "Default options to the terminal. `-e' aka `--command'.")
-
-(defun find-terminal ()
-  "Return the first terminal emulator found on the system from the `*visual-terminal-emulator-choices*' list."
-  (loop for program in *visual-terminal-emulator-choices*
-     when (which:which program)
-     return program))
-
-(defun visual-command-p (text)
-  "The command TEXT starts by a known visual command, listed in `*visual-commands*'."
-  (let* ((cmd (string-left-trim "!" text)) ;; strip clesh syntax.
-         (first-word (first (str:words cmd))))
-    ;; This will be smarter. https://github.com/ruricolist/cmd/issues/10
-    (find first-word *visual-commands* :test #'equalp)))
-
-(defun run-visual-command (text)
-  "Run this text command into another terminal window."
-  (let ((cmd (string-left-trim "!" text)))
-    (uiop:launch-program `( ,(find-terminal)
-                             ;; quick way to flatten the list of switches:
-                             ,@*visual-terminal-switches*
-                             ,cmd))))
diff --git a/shell-utils.lisp b/shell-utils.lisp
new file mode 100644
index 0000000..92028ec
--- /dev/null
+++ b/shell-utils.lisp
@@ -0,0 +1,126 @@
+(in-package :sbcli)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;; Run visual / interactive / ncurses commands in their terminal window.
+;;;
+;;; How to guess a program is interactive?
+;;; We currently look from a hand-made list (à la Eshell).
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;; thanks @ambrevar: https://github.com/ruricolist/cmd/issues/10
+;; for handling command wrappers (sudo) and vterm.
+
+(defparameter *visual-commands*
+  '(;; "emacs -nw" ;; in eshell, see concept of visual-subcommands.
+    "vim" "vi"
+    "nano"
+    "htop" "top"
+    "man" "less" "more"
+    "screen" "tmux"
+    "lynx" "links" "mutt" "pine" "tin" "elm" "ncftp" "ncdu"
+    "ranger"
+    ;; last but not least
+    "ciel-repl")
+  "List of visual/interactive/ncurses-based programs that will be run in their own terminal window.")
+
+(defun vterm-terminal (cmd)
+  "Build a command (string) to send to emacsclient to open CMD with Emacs' vterm."
+  (list
+   "emacsclient" "--eval"
+   (let ((*print-case* :downcase))
+     (write-to-string
+      `(progn
+         (vterm)
+         (vterm-insert ,cmd)
+         (vterm-send-return))))))
+
+(defparameter *visual-terminal-emulator-choices*
+  '("terminator" "x-terminal-emulator" "xterm" "gnome-terminal"
+    #'vterm-terminal)
+  "List of terminals, either a string or a function (that returns a more complete command, as a string).")
+
+(defparameter *visual-terminal-switches* '("-e")
+  "Default options to the terminal. `-e' aka `--command'.")
+
+(defvar *command-wrappers* '("sudo" "env"))
+
+(defun find-terminal ()
+  "Return the first terminal emulator found on the system from the `*visual-terminal-emulator-choices*' list."
+  (loop for program in *visual-terminal-emulator-choices*
+     if (and (stringp program)
+             (which:which program))
+     return program
+     else if (functionp program) return program))
+
+(defun basename (arg)
+  (when arg
+    (namestring (pathname-name arg))))
+
+(defun shell-command-wrapper-p (command)
+  (find (basename command)
+        *command-wrappers*
+        :test #'string-equal))
+
+(defun shell-flag-p (arg)
+  (str:starts-with-p "-" arg))
+
+(defun shell-variable-p (arg)
+  (and (< 1 (length arg))
+       (str:contains? "=" (subseq arg 1))))
+
+(defun shell-first-positional-argument (command)
+  "Recursively find the first command that's not a flag, not a variable setting and
+not in `*command-wrappers*'."
+  (when command
+    (if (or (shell-flag-p (first command))
+            (shell-variable-p (first command))
+            (shell-command-wrapper-p (first command)))
+        (shell-first-positional-argument (rest command))
+        (first command))))
+
+(defun shell-ensure-clean-command-list (command)
+  "Return a list of commands, stripped out of a potential \"!\" prefix from Clesh syntax."
+  (unless (consp command)
+    (setf command (shlex:split command)))
+  ;; remove optional ! clesh syntax.
+  (setf (first command)
+        (string-left-trim "!" (first command)))
+  ;; remove blank strings, in case we wrote "! command".
+  (remove-if #'str:blankp command))
+
+(defun visual-command-p (command)
+  "Return true if COMMAND runs one of the programs in `*visual-commands*'.
+  COMMAND is either a list of strings or a string.
+`*command-wrappers*' are supported, i.e. the following works:
+
+  env FOO=BAR sudo -i powertop"
+  (setf command (shell-ensure-clean-command-list command))
+  (let ((cmd (shell-first-positional-argument command)))
+    (when cmd
+      (find (basename cmd)
+            *visual-commands*
+            :test #'string=))))
+
+(defun run-visual-command (text)
+  "Run this command (string) in another terminal window."
+  (let* ((cmd (string-left-trim "!" text))
+         (terminal (find-terminal)))
+    (if terminal
+        (cond
+          ((stringp terminal)
+           (uiop:launch-program `(,terminal
+                                  ;; flatten the list of switches
+                                  ,@*visual-terminal-switches*
+                                  ,cmd)))
+          ((functionp terminal)
+           (uiop:launch-program (funcall terminal cmd)))
+          (t
+           (format *error-output* "We cannot use a terminal designator of type ~a. Please use a string (\"xterm\") or a function that returns a string." (type-of terminal))))
+        ;; else no terminal found.
+        (format *error-output* "Could not find a terminal emulator amongst the list ~a: ~s"
+                '*visual-terminal-emulator-choices*
+                *visual-terminal-emulator-choices*))))
+
+#+(or)
+(assert (string-equal "htop"
+                      (visual-command-p "env rst=ldv sudo htop")))
diff --git a/src/ciel.lisp b/src/ciel.lisp
index a703e86..b7efbd1 100644
--- a/src/ciel.lisp
+++ b/src/ciel.lisp
@@ -1,6 +1,8 @@
+
 (in-package :cl-user)
 (defpackage ciel
-  (:use :cl))
+  (:use :cl)
+  (:export :enable-shell-passthrough))
 
 (in-package :ciel)
 
@@ -332,3 +334,7 @@ We currently only try this with serapeum. See *deps/serapeum/sequences-hashtable
 
 (when *pretty-print-hash-tables*
   (toggle-pretty-print-hash-table t))
+
+(defun enable-shell-passthrough ()
+  "Enable the shell passthrough with \"!\". Enable Clesh's readtable."
+  (named-readtables:in-readtable clesh:syntax))