Here’s what the standard md5sum output looks like:

$ md5sum test.txt
d0ea20794ab78114230ba1ab167a22c2 test.txt

Now here’s what the output of md5 on Mac OS X looks like:

$ md5 test.txt
MD5 (test.txt) = d0ea20794ab78114230ba1ab167a22c2

While this normally wouldn’t be a big deal, it can cause major issues if you’re trying to run scripts that were written for a Unix-like environment which expect the default md5sum format.

Thankfully, md5 has a switch that reverses the output:

$ md5 -r test.txt
d0ea20794ab78114230ba1ab167a22c2 test.txt

If you’d like to permanently change md5′s behavior to mimic that of md5sum, you have two options:

The first is to simply add the following alias to ~/.profile:

alias md5sum='md5 -r'

Now when you type ‘md5sum test.txt‘, the command will be replaced with ‘md5 -r test.txt‘. However, this may not work with your scripts.

The second solution, and my preferred method, is to create a small script called md5sum that contains the following:

#!/bin/bash
/sbin/md5 -r "$@"

I then make this script executable (chmod +x md5sum) and put it in /sbin/. Now, whenever a script calls md5sum, the small bash script above is used and it produces output identical to that of md5sum on other Unix systems.

If you want to change the default application used to open all files with a specific extension, the steps are slightly different:

Select the file and choose File -> Get Info (or Cmd+i) and expand the Open With section:

From here, select the application you want to use for opening those file types and then click Change All. This will update the OS X Launch Services Database, which is consulted when opening files. Now all files with that extension will be opened with the application you selected.

Note: The steps below were used to prepare a MacBook Pro running OS X Leopard for resale. Although the steps are similar for other versions of OS X, I have only tested them with Leopard. (Update: Matt mentioned in the comments that he successfully used these steps on OS X 10.6.)

Backup Your Data

If the Mac you’re reselling is your own, you should do a full system backup before proceeding.

My favorite method for doing this is to use an external USB hard drive and Carbon Copy Cloner (free). Carbon Copy Cloner can be used to take a snapshot of your entire drive and make it bootable. This means you can actually boot from your backup drive, given you’re booting from identical hardware. At the very least, you’ll have an identical copy of everything on the computer.

You can also use Time Machine to backup your data. I don’t use Time Machine, so I cannot recommend it.

The bottom line is, you want to backup anything important on the Mac you’re reselling because the next steps will erase everything.

Reinstall Mac OS X Leopard

1. Insert Mac OS X Leopard Install Disc
2. Restart the computer
3. Hold down the Option key while the computer is restarting. The system will then prompt you to select a startup disk. Choose the Mac OS X Leopard Install Disc.
4. On the “Select a Destination” screen, click “Options” and choose “Erase and Install”. This will ensure a clean installation of Mac OS X Leopard.
5. Follow the remaining steps to install Mac OS X; they are all self explanatory.
6. When the installation finishes, the Mac will reboot and you’ll be presented with the Setup Assistant.

If you’re not interested in installing the software updates or any additional software, press Command+Q to quit the Setup Assistant and choose Shutdown. The next time you turn on the machine, the Setup Assistant will launch again.

Install Software Updates & Additional Software

If you want to be super nice to the new owner of your Mac, you’ll need to complete the Setup Assistant and create a temporary user. We will use that user to download and install the software updates as well as install any additional applications (Firefox, MS Office, etc.). Once we’re done updating the system and installing software, we’ll delete the temporary user and reset the Setup Assistant.

1. Complete the Setup Assistant and create the first user account (we’ll delete this user and reset the Setup Assistant later, so it doesn’t matter what you use). Make note of the shortname for the user you create as we’ll need that in the next section (e.g., user “Raam Dev” will probably have a shortname of “raamdev”).
2. At this point, you should be logged into the newly reinstalled system using the temporary account you created.
3. Connect to the Internet (using a wired or wireless connection)
4. Run Software Update (Apple Icon -> Software Update) and install any available updates. This may take awhile!
5. After the system reboots, run Software Update again. There will most likely be more updates to install. Repeat this process until there are no more updates to install.
6. Install any additional applications, being sure to install for “All Users” if prompted. Also, make sure the new applications are installed in /Applications/ and not ~/Applications/

Clean Up and Reset the Setup Assistant

Now that we’ve installed the latest updates and installed any additional software, we need to clean things up. First, we’ll delete the temporary user we created and then we’ll reset the Setup Assistant to ensure it launches the next time we boot up.

First, you’ll need to start the Mac in Single User mode by restarting and holding down Command+S. This mode does not have a graphical user interface (GUI) and is entirely command-based.

Once you’re in Single User mode, run the following commands and press Enter at the end of each line. (Note: The $ represents the command prompt; you don’t actually type the $.)

By default, the hard drive is mounted as read-only in Single User mode. Before we continue, we need to make the disk writable:

$ mount -uw /

Next, we clean up that temporary user we created. Replace USERNAME with the shortname of the user you created in the previous section.

$ rm -R /Library/Preferences/
$ rm -R /Users/USERNAME/
$ /bin/launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist &
$ dscl . -delete /Users/USERNAME

And lastly, we need to reset the Setup Assistant so it runs the next time we start the Mac:

$ rm /var/db/.AppleSetupDone

Now that everything is cleaned up and the Setup Assistant has been reset, we can shutdown the system and ship or deliver the Mac to its new owner!

$ shutdown -h now

If you want to boot the Mac to make sure it looks the way it should when the user gets it (i.e., the intro video and Setup Assistant start), just make sure you press Command+Q and choose Shutdown.

Unfortunately, the maximize button in iTunes only cycles through Previous Size and the Mini Player mode; at no point does it actually maximize the window to fit the screen!

Note: As Ondrej commented below, you might be able to fix this by simply holding down the Alt/Option key and pressing the zoom/maximize button (the green button).

I tried installing an application called RightZoom which changes the behavior of the maximize button in OS X by maximizing the window to fill the screen (as opposed to simply maximizing for “best fit”). However, that did nothing to change the behavior of iTunes.

After searching the web for solutions and finding nothing, I remembered a trick I had used in the past on Windows computers: Change the display resolution to something smaller, thereby forcing the operating system to resize windows to fit the new resolution. Then, after the OS resizes the windows, change the resolution back to the original. Of course this only works if the original resolution is not already set for the lowest one (it most likely isn’t).

To my relief, this trick worked perfectly! When I switched to a smaller resolution, the iTunes window was resized to fit the smaller screen.

For your reference, here are the steps:

1. Launch System Preferences -> Displays
2. Select a smaller resolution
3. iTunes (or any other application) will be resized to fit the smaller resolution
4. Change the resolution back to the default
5. Oversized window problems solved!

CVE-2008-5353 is a critical Java vulnerability that was discovered back in August 2008 and patched by Sun Microsystems a few months later. However, Apple has failed to release a patched version of Java, even in the latest 10.5.7 update! CVE-2008-5353 is described as follows:

Unspecified vulnerability in Java Runtime Environment (JRE) for Sun JDK and JRE 6 Update 10 and earlier; JDK and JRE 5.0 Update 16 and earlier; and SDK and JRE 1.4.2_18 and earlier allows untrusted applets and applications to gain privileges via unknown vectors related to “deserializing calendar objects.”

Since Apple failed fix this vulnerability in the latest update to OS X (10.5.7), Landon Fuller, a programmer and former Apple Engineer, released a proof-of-concept demonstrating the exploit. The demonstration is done by launching a Java applet in your web browser and using the exploit to run the /usr/bin/say command on your Mac to “speak” some words through your speakers. This may not sound very dangerous, but this same exploit could be used to run malicious code on your Mac without your even knowing it!

So, how can I protect myself?

For now, all you can do is entirely disable Java in your browsers to ensure no Java applets are allowed to run. The good news is that chances are you probably don’t depend on Java anyway (remember, Java is not JavaScript). And if you find yourself needing to run something that does require Java (the browser will alert you with a message saying the Java plugin isn’t installed), you can always re-enable Java in your browser while you’re using the applet, and then disable it again when you’re done. Inconvenient, yes, but worth it. This is one nasty vulnerability, and with all the publicity it’s been getting lately, there’s bound to be more malicious code in the wild just waiting to hijack your system.

Disabling Java in Firefox

In Firefox, choose from the menu, Firefox -> Preferences. Then select the Content tab and un-check the Use Java option:

Disabling Java in Safari

(applies to both Safari 3 and Safari 4 Beta)

In Safari, choose from the menu, Safari -> Preferences. Then select the Security tab and un-check the Enable Java option:

Update: TidBITS writes that Apple has released a patched version of Java that fixes this issue. It is available through Software Update.

Download & Install Software

1. Download MacTheRipper (v2.6.6 is listed on that site but I’m using v3.0. Search BitTorrent for the newer version if you’re interested.)
2. Download HandBrake (I’m using v0.9.3)
3. Install the above applications

Rip the DVD Using MacTheRipper (what an awesome name!)

1. Insert the DVD
2. OS X will automatically start playing the DVD. Press CMD+Q to quit the application.
3. Launch MacTheRipper (and be careful he doesn’t hurt you)



4. Leave the default options and select File -> Save To…
5. Create a new directory to temporarily store the raw contents of the DVD and select it
6. Click Open. MacTheRipper will automatically start ripping the raw contents of the DVD to the directory you selected
7. When the ripping finishes, quit MacTheRipper

Convert the Raw DVD Data to MPEG-4 Using HandBrake

1. Launch HandBrake (don’t break your hand)
2. Upon launching, you should be presented with the Open dialog. You want to select the directory to which you ripped the DVD using MacTheRipper. Note: Select the directory that contains the VIDEO_TS directory, but not VIDEO_TS directory itself! The other directories contain important data, such as AUDIO_TS for audio data.
3. Click Open and HandBrake will scan the various titles in the raw data. When finished, you’ll be left with the main HandBrake screen



4. The correct title should already be selected and it should be the longest one in the list. If it’s a 2-hour DVD, you don’t want to select the title that says 1 minute. There may be lots of short titles mixed in and these may be extras on the DVD or previews.
5. After you’ve selected the correct title, choose browse and select a location where you want to save the converted video. After selecting the location, you can change the filename or leave the default. I like to store various bits of information in the video filename, such as the year the video was released, whether it’s widescreen or full screen, and the codec and audio formats. For example:

   Gattaca.1997.WS.DVDRip.XviD.AC3.avi

6. Now select the format. I usually choose AVI for the best compatibility.
7. For video codec, choose “MPEG-4 (XviD)”
8. Next to “Quality:”, select “Target size (MB)” and use the following guidelines. I like to retain as much of the quality as possible, so I follow these rules. Remember, the higher the file size, the better the quality. If you don’t care so much about quality or don’t have lots of free space, you can just use 700MB for DVDs. I use 1400MB for DVDs, and smaller sizes for TV/Documentary or episodic movies.

   Here are the sizes I use depending on the length of the movie or episode:

   175MB (20-30 mins)
   350MB (40-55 mins)
   1400MB (90 min+), also known as 2CD quality

9. Click the “Audio & Subtitles” tab
10. Choose the best audio source quality available. Sometimes the DVD will contain 6-Channel 5.1 audio, but it won’t be selected by default.
11. If it’s available, select “AC3 Passthru” under “Audio Codec”.



12. With everything configured, click Start. If you’re converting a DVD that is a collection of shorter movies (like the Outer Limits DVD I’m ripping in the example), you can simply click “Add to Queue”, repeat the above process for each of the titles, and then click Start when everything is queued up. If you plan to do this though, you should definitely convert at least one episode first to make sure it comes out correct.

Depending on the speed of your computer, the quality, and the length of the movie you’re converting, this process could take anywhere from 30 minutes to 3 hours.

When HandBrake finishes, try watching the resulting AVI and make sure it plays correctly (with sound and all). If you’re not happy, delete it and repeat the process again. Once you’re happy with the AVI, you can delete the raw data that you ripped earlier with MacTheRipper (it takes up 6-7GB of space!).