Counting Color Pages in PDF Files

Printing books and such in color can be expensive. So here is how to count the color pages using a recent version of GhostScript and a UNIX shell:

gs -o - -sDEVICE=inkcov input.pdf | grep -v "^ 0.00000  0.00000  0.00000" | grep "^ " | wc -l

Improved handling of background GNU Global update

Earlier this year I detailed how to run gtags of GNU Global when Emacs is idle. However, this collides with some special Emacs modes, like ediff. That mode makes its own Emacs frame layout, which can be destroyed by the xgtags incremental update buffer. So I conceived a way to disable gtags temporarily as long as ediff is active:

;; This stuff is only needed, if you haven't got xgtags loaded yet
(autoload 'gtags-mode "gtags" "" t)
(require 'xgtags)
(add-hook 'c-mode-common-hook (lambda () (xgtags-mode 1)))
(defun global-update-incrementally () (shell-command "global -u -q" "*Messages*" "*Messages*") )

;; Call gtags update when idle for some time
(defcustom my-gtags-update-idle-time 60
  "Number of idle seconds before an incremental gtags update is launched"
  :group 'my-group
  :type 'integer
  )

;; initially allow gtags updates
(setq my-gtags-update-active t)

(run-with-idle-timer my-gtags-update-idle-time t
                     (lambda ()
                       (if (and my-gtags-update-active
                                (not (minibufferp) )
                                )
                           (progn
                             (message "Running gtags...")
                             (global-update-incrementally)
                             )
                         )
                       )
                     )

(add-hook 'ediff-quit-hook 
          (lambda () 
            (message "Activating gtags update.")
            (setq my-gtags-update-active t) 
            )
          )

(add-hook 'ediff-before-setup-hook 
          (lambda () 
            (message "Deactivating gtags update.")
            (setq my-gtags-update-active nil) 
            )
          )