May 12 2008
Login Screenshot Challenge
In my last post I was showing various options for working with the root account. Near the end of the post I was planning to show how when logging in as root, the login dialog does not offer root as one of the available login names (instead, the name Other is listed).
Attempting to capture the login screen has been an interesting diversion. Up to this point I’ve been unsuccessful in capturing the elusive screenshot.
So here’s a challenge for you…can you be the first to figure out how to capture a screenshot of the login screen? There are a couple of ground rules:
- You must be running Leopard (or at a minimum, the solution must work on Leopard).
- Since I want to show how the login screen does not display root as one of the available login accounts, the screenshot will have to be of the login window. Put another way, simply selecting a name from the drop-down of the fast user switching dialog is not an option.
- I’d like this to be a “free” solution, as in, no software to buy.
- Finally, I am looking for a solution that doesn’t require more than one Mac (e.g. using SSH from one Mac to another).
To save you some time, I’ve listed below the options I’ve tried:
Attempt #1 - Hotkeys
From the login screenscreen, I tried the following hotkeys:
- Shift+Command+3 (capture entire screen to file)
- Control+Shift+Command+3 (capture entire screen to clipboard)
- Shift+Command+4 (capture area defined with mouse to file)
Each of the above greeted me with a pleasant beep, nothing more.
Attempt #2 - Grab application
My next attempt was to try the timed capture option with the Grab application. Seemed like a clever idea, however, when I started the timer and logged out (to get to the login screen), Grab just seems to quietly go away. No warning, no error, no screenshot.
Attempt #3 - Fast Switching
Next, I enabled fast user switching. My thinking was, maybe if I don’t logout per se, and request the Login Window (see the figure below) that the login screen might somehow be different (as in, something I can capture using hotkeys):

Seemed logical, however, upon choosing Login Window I was shuffled over to the same login screen as if logging out. No luck.
Attempt #4 - Getting a little more creative, I tried this from within a terminal:
screen -d -m bash -c “sleep 30; screencapture /Users/John/login.png”
This option uses a screen manager (more on that in an upcoming post) and calls the screencapture application after sleeping for 30 seconds. Once I ran this option from a terminal, I quickly logged out and patiently waited…I heard the camera sound of the screencapture application and was psyched, “yes!”…I navigated to my home directory and located the file login.png…I opened the file with the Preview application…and much to my dismay…it was an image alright…a big, black, blank image. So close, but no cigar.
So, now it’s up to you. Can you figure what it takes to capture the login screenshot? You can submit your idea as a comment (below) or drop me an email. And please verify your trick works with Leopard, as other published solutions I’ve found seem to work only on releases prior to Leopard.
I’m doing my best to see if I can find a volunteer to donate a prize (software, book, t-shirt, etc). If that doesn’t come through, what I can offer is a little lime-light, blog style. If you are the first to contact me with a solution (within the parameters above), we can collaborate on a post where you can tell the world how you got so smart :) and share your bio, picture, blog/website, etc.
If anyone reading is interested in donating a prize, contact me and we’ll get the ball rolling.
I am very intrigued to see if/how this can be done.






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