Emacs function to add new path elements to the $PATH environment variable

A very simple eLisp function to add new path elements to the PATH environment variable. Very useful for adding new comint executables from within .emacs/init.el files.

(defun my-add-path (path-element)
 "Add the specified path element to the Emacs PATH"
  (interactive "DEnter directory to be added to path: ")
  (if (file-directory-p path-element)
    (setenv "PATH"
       (concat (expand-file-name path-element)
               path-separator (getenv "PATH")))))

Quickly diff the changes made in the current buffer with its file

Update (23rd Jan 2010): Separated the key-assignment and  function definition.

A simple function to quickly do a diff of the current buffer contents with its underlying file. Very useful if the file has been changed outside (e.g., a log file).

;; Diff the current buffer with the file contents
(defun my-diff-current-buffer-with-disk ()
 "Compare the current buffer with it's disk file."
 (diff-buffer-with-file (current-buffer)))
(global-set-key (kbd "C-c w") 'my-diff-current-buffer-with-disk)

Google Search from within Emacs

A quick and dirty eLisp function for searching on the internet from within Emacs. The default is to search using Google, but you can add to the *internet-search-urls* variable to setup additional search URLs.

By default, the search term is appended at end of the URL – however, you can also encode the specific search term insertion point in the URL by marking the position using the “%s” marker.

;;; The custom search URLs
(defvar *internet-search-urls*
 (quote ("http://www.google.com/search?ie=utf-8&oe=utf-8&q=%s"

;;; Search a query on the Internet using the selected URL.
(defun search-in-internet (arg)
 "Searches the internet using the ARGth custom URL for the marked text.

If a region is not selected, prompts for the string to search on.

The prefix number ARG indicates the Search URL to use. By default the search URL at position 1 will be used."
 (interactive "p")

 ;; Some sanity check.
 (if (> arg (length *internet-search-urls*))
      (error "There is no search URL defined at position %s" arg))

  (let ((query                          ; Set the search query first.
    (if (region-active-p)
      (buffer-substring (region-beginning) (region-end))
    (read-from-minibuffer "Search for: ")))

  ;; Now get the Base URL to use for the search
  (baseurl (nth (1- arg) *internet-search-urls*)))

  ;; Add the query parameter
  (let ((url
    (if (string-match "%s" baseurl)
      ;; If the base URL has a %s embedded, then replace it
         (replace-match query t t baseurl)
    ;; Else just append the query string at end of the URL
      (concat baseurl query))))
   (message "Searching for %s at %s" query url)
   ;; Now browse the URL
   (browse-url url))))

gnuplot with AquaTerm on OSX Snow Leopard

The gnuplot graphing utility has always had excellent support for multiple terminal types. While the X11 terminal is a satisfactory GUI view for the graphs, I prefer to use the AquaTerm terminal on OSX as it is more ‘Mac-like’ and feels more natural.

Also, I do prefer to compile gnuplot by myself on OSX rather than downloading the pre-packaged binaries – as this gives me more control over the compilation (including getting around the stupid Apple readline bug – where Apple has essentially shipped a broken readline by using libedit to emulate the non-existent libreadline).

This local compile requires that AquaTerm be installed so that the library dependencies for aquaterm exists in:


and the corresponding headers are available at:

In addition, the AquaTerm.app itself resides in /Applications.

However, on OS X Snow Leopard, there is a catch – the version of AquaTerm is 32 bit, whereas the default compilation of gnuport results in a 64-bit version – which is not able to load the 32-bit libaquaterm dynamic libraries.


In such a case, the gnuplot compilation does succeed – however, the default terminal becomes the X11 version – which is back to square-one.

A darwinports port does exist for gnuplot – however, as mentioned in an earlier post, this port seems to depend on half of the port repository (i.e., a ton of stuff you do NOT want gets installed as well).

However, there is a easier way to get around this situation. Here’s how.

  1. First install the default binary for AquaTerm from SourceForge and install normally. This step is to basically setup the right folders and symlinks so that you do not have to muck with these later
  2. Now install AquaTerm again from Darwinports – this port has the correct patches needed – and more importantly – builds a 64 bit version by default. This will also install the application under /Applications/MacPorts/


  1. Now comes the fun part. We will replace two folders from the darwinports version to the previously installed AquaTerm.
    • Step 1: Replace /Library/Frameworks/AquaTerm.framework with /opt/local/Library/Frameworks/AquaTerm.framework. This will ensure that the correct 64 bit AquaTerm libraries get referenced by the gnuplot compilation
    • Step 2: Replace /Applications/AquaTerm.app with /Applications/MacPorts/AquaTerm.app. This will ensure that the correct 64-bit AquaTerm binary is in the correct location
    • Step 3 (Optional): You can now uninstall the darwinports version by running sudo port uninstall aquaterm from a terminal window
  2. Download the source code for gnuplot and extract the same.
  3. Run ./configure (using a command line parameter to ignore the broken Apple readline) and then make and make install (install will happen in /usr/local)


That’s it! The compilation should now succeed and gnuplot will be linked with the correct 64-bit aquaterm dynamic library. Enjoy!


RIP Mafia Wars. Was nice knowing you.

With a heavy heart and spasms of grief and guilt, I finally managed to delete Mafia Wars from my Facebook account. It was nice while it lasted – but the horror of the Lost Hours! The incessant and obsessive desire to click-click-click and level up – only to find …. more of the same thing. This is addiction.

For good measure, have parted company with Farmville (which thankfully was only a 2 minute fad) and a few other data grabbing apps too. Finally can get back to the Face of Facebook.

Adios Mafia Wars; may you R.I.P.

Snow Leopard – First Impressions

I finally bit the bullet and installed Snow Leopard over last weekend. I did a clean install (i.e., reformat and install afresh) – considering the significant under-the-hood changes that this OS revision has.

The basic steps I followed are:

  1. Cleaned up the existing Leopard install to remove applications, preference panes and documents I did not need
  2. Reviewed the preferences under ~/Library/Preferences as well as the application support items under ~/Library/Application Support and removed the items which were out of date or detritus from old installs
  3. Took an image backup using SuperDuper! of the Leopard install
  4. Took a backup of the disk using Time Machine to allow easier data restore during the installation
  5. De-authorized my iTunes to prevent increment of the install counter after reinstall of the OS
  6. Popped in the Snow Leopard DVD and started the install
  7. During installation, I used the Disk Utility to reformat the Mac OS partition
  8. I also did a custom install to prevent the printer drivers (over 2 GB) being installed. In addition, I selected the optional Rosetta and Quicktime 7 components (seriously Apple, these take less than 10 MB – why the optional tag?)
  9. Waited for around 20 minutes to have the base image installed, and then used the migration assistant to restore data from my Time Machine backup

The install was relatively smooth, and restoring the data from my Time Machine backup also went without any issues. However, post-install, some of the glitches started appearing:

  1. The default font for Safari as well as Firefox went crazy – with large bold fonts appearing. It turned out to be a font substitution issue with the Arial font, which for some reason was missing the “Regular” type. Restored the font from the old image backup and every thing was back to normal. It appears a lot of people are facing this issue
  2. Adobe’s Photoshop Elements 6 refused to start, stating expiry of the license. This also is a known issue, and a restore of the /Library/Application Support/FLEXnet Publisher/ folder from the image backup made things normal again
  3. The key chain was not allowing storage of any new passwords, and was also not allowing viewing of the stored passwords. This is a known issue and my solution was to simply change the login keychain password once and reset it back again to the original password
  4. Emacs 23 was not compiling under Snow Leopard. There is already a patch available in CVS. However, there are incompatibilities with the 64 bit GCC – hence you need to pass a CC=“gcc -arch i386” as part of the ./configure invocation. The compilation succeeded with this. Note that a recompile of some of the user installed lisp packages was required (notably Icicles)

Other than the issues listed. rest of the experience seems OK so far. The look and feel is not too different and most of the user visible changes are subtle – except for the new QuickTime Player – which is a dumbed down and dressed up version of the venerable QT Player.

In summary, this is an OS upgrade that does have the potential to break some of the old applications, though most of the issues do seem to have work arounds – it is also going to become a required update pretty soon – given the internals changes that Apple has made. No need to rush out right now (mea culpa!) to upgrade – but do be prepared to do the update in the near future.