Following the frustrating experience of having my MacBook shutting down without warning, I came across a terminal command that “tests” if your MacBook suffers from the issue. I thought I’d share this with everyone considering that many MacBook owners may not even be aware that their MacBook is faulty until it shuts down on them.

More after the jump.


Step 1
Open up Terminal. (You can load it up through Spotlight)

Step 2
Type in the following command:

yes >/dev/null &

and hit return. This will make maximum use one of the two processor cores of the MacBook.

Step 3
In the same terminal window, type in the command in Step 2 once again and hit return.

yes >/dev/null &

Your MacBook will now be making use of both processor cores and shortly after, you should hear the fans kick in pretty loudly.

I recommend you leave it running (keep the Terminal window open) for at least 15 minutes.

Step 4
If your MacBook has not suffered a random shut down after the 15 minutes, quit Terminal (⌘+Q).

The fans should get back to normal within a couple of minutes of quitting Terminal.

Now, simply leave your MacBook on and wait to see if it shuts down randomly. If it does suffer a random shut down, it’s likely to be within the next 20 minutes.

You can use your MacBook normally while waiting although I recommend you don’t work on anything important during that time. Normal web browsing is fine.

Step 5
If your MacBook still has not suffered a random shut down, repeat Steps 1 to 4 at least two more times. And if your MacBook survives those, then I would say it’s reasonable to say that it does not suffer from the Random Shutdown.

How this “test” works?
The yes command is typically a fairly useless one. It simply outputs a series of ys to the screen until you quit the command. You can find out more about it on Matt Welsh’s website.

This test works by putting the processor in your MacBook to work using the yes command. As it does the processing, the processor’s temperature rises and when you quit terminal the temperature of the processor decreases. This process (which happens under normal usage) somehow triggers a random shutdown in faulty MacBooks.

What to do if your MacBook shutsdown randomly?
If your MacBook fails this test (i.e. it shutdown during one of the above steps), contact Apple and arrange for a replacement or a repair.

Also, please let me know at which point/step your MacBook suffered the shutdown in the comments below or make a post at to share your experience/frustration.

The Apple Files or Techpaedia accepts no responsibility for any damage or loss that you may incur by following the above steps. Do so at your own risk. We also do NOT guarantee that your MacBook is free from what we refer to as Random Shutdown even if it passes this test. This test is for investigational purposes only.

[Via Jon’s Comment over at]

Related Posts:
MacBook Random Shutdown List
MacBook Random Shut Down
Macbook Gone for Repairs
Life is Random
~10% of MacBooks (13″) have Random Shutdown

Update: Apple have released a firmware update to address the Random Shut Down problems.