Revised installation instructions for macOS

module2/ressources/emacs_orgmode.org

@@ -55,26 +55,41 @@ emacs -batch --funcall "org-version" 2>&1 | grep version
 The version numbers you get will depend on the distribution you are
 running. _You really want to make sure you do not rely on org-mode 8_,
 which is now deprecated. 
-** Mac OS X
+** macOS
+*Note:* macOS comes with a prehistoric command-line-only version of Emacs located at /usr/bin/emacs. It's best to forget about it.
+
 - *Option 1*: Install the =.dmg= file from [[http://vgoulet.act.ulaval.ca/][Vincent Goulet]]:
   https://vigou3.github.io/emacs-modified-macos/. It ships with recent
   versions:
   - Emacs 26.1
   - Org-mode 9.1.13
   - ESS 17.11
-  In that case you may have several versions of emacs installed on
-  your machine and launching emacs from a terminal may not run the one
-  you just installed. If anyone know how to get rid of this...
-- *Option 2*: If you already use =brew=, simply do the following
+
+  If you install this version of Emacs, or in fact any other version of
+  Emacs distributed as a clickable application in a =.dmg= file,
+  you must type the full path to the executable if you want to run
+  Emacs from a terminal. For example, if your clickable application
+  is at =/Applications/Emacs.app=, then the executable is at
+  =/Applications/Emacs.app/Contents/MacOS/Emacs=
+
+- *Option 2*: If you use [[https://docs.brew.sh/][Homebrew]], do the following:
   #+begin_src sh :results output :exports both
   brew update
-  brew install emacs [--with-cocoa]
+  brew install emacs --with-cocoa
   brew linkapps emacs
-  brew tap homebrew/science
-  brew install ess
-  brew install auctex # The name may be slightly more complicated here
   brew install wget
+  brew tap dunn/emacs
+  brew install auctex
+  brew tap brewsci/science
+  brew install ess
+  #+end_src
+  This provides an =emacs= command for use from the command line, plus a clickable application at =Cellar/emacs/26.1_1/Emacs.app= inside your Homebrew directory. If
+  you installed Homebrew at the default location =/usr/local=, then this is =/usr/local/Cellar/emacs/26.1_1/Emacs.app=.
+  If you installed Homebrew on an account with administrator privileges, you can add
+  #+begin_src sh :results output :exports both
+  brew linkapps emacs
   #+end_src
+  in order to make Emacs accessible directly from =/Applications=.
 ** Windows
 Install the =.exe= file from [[http://vgoulet.act.ulaval.ca/][Vincent Goulet]]:
 https://vigou3.github.io/emacs-modified-windows/. It ships with recent