This isn't exactly what was asked for, but because I live in emacs I don't get much value being able invoke it from the command line. If that's ok, try this..

  (defvar org-journal-file "~/Dropbox/org/engjournal.org"  
    "Path to OrgMode journal file.")  
  (defvar org-journal-date-format "<%Y-%m-%d %a %I:%M %p>"  
    "Date format string for journal headings.")  

  (defun org-journal-entry ()  
    "Create a new diary entry for today or append to an existing one."  
    (interactive)  
    (switch-to-buffer (find-file org-journal-file))  
    (widen)  
    (let ((today (format-time-string org-journal-date-format)))  
      (beginning-of-buffer)  
      (unless (org-goto-local-search-headings today nil t)  
 ((lambda ()   
    (org-insert-heading)  
    (insert today)  
    (insert " "))))  
      (beginning-of-buffer)  
      (org-show-entry)  
      (org-narrow-to-subtree)  
      (end-of-buffer)))  

  (global-set-key "\C-cj" 'org-journal-entry)

So, C-cj will open the file, create a timestamp entry at the top, and narrow to the subtree. Great for creating timestamped notes. I keep a journal this way (multiple entries per day are fine), but it could be used for any note taking.