Mac OS X Startup Modifier Keys
TMO Quick Tip - Mac OS X Startup Modifier Keys
by , 7:30 AM EDT, April 6th, 2007
For the most part, starting up your Mac involves nothing more than pressing the power button, and away you go. But there are a few options for modifying how your Mac starts up - if you know which keys to press.
 The Mac OS X Finder |
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Here's how this works: Start up your Mac, and as soon as you hear the familiar chime, press and hold the modifier key combination to alter what happens when Mac OS X boots.
- C The C key tells your Mac to bypass its default startup volume and boot from a CD or DVD with a system folder.
- T Use the T key to boot into target disk mode. This lets you plug your Mac into another Mac with a FireWire cable. Your Mac will appear as a hard drive on the other Mac's Desktop.
- Shift Holding down the Shift key after startup disables non-essential kernel extensions and login items until your reboot. This is called Safe Boot, and is handy for troubleshooting system-related problems. If the issue goes away during a Safe Boot, odds are it is related to a login item, or a bad kernel extension that an application installer tossed into your system folder.
Variation on a theme: Wait until after you see the blue startup screen, and then hold down the Shift key. This lets all system-level extensions and login items load, but prevents anything that loads when you log in from launching. - Command-Option-Shift-Delete This finger-origami keyboard combination tells your Mac to bypass your default startup volume and look for any bootable disk, CD, or DVD it can find.
- Command-S The Command-S keyboard combination tells your Mac to boot into Single User Mode, which is actually a Unix command line. This is another useful key combo for troubleshooting system problems. If you aren't comfortable mucking around a Unix command line, this is a good one to avoid.
- Command-V Verbose Mode, invoked with the Command-V keyboard combination, was something I relied on all the time in the early and rough days of Mac OS X since it lists everything that is loading and launching during the startup process. It was a lifesaver for troubleshooting a horked Mac OS X 10.1 installation on many occasions for me.
- X Holding down the X key during startup was also handy during the early days of Mac OS X when we had Macs that could also boot Mac OS 9. If your Mac OS 9 System Folder was damaged and your Mac wouldn't boot, you could use the X key to force your Mac to boot Mac OS X.
If there is another startup keyboard sequence you like to use, feel free to share it below.
Jeff Gamet is TMO's Morning Editor and Reviews Editor. He lectures, teaches and speaks on Mac OS X and design-related topics, and is the author of The Designer's Guide to Mac OS X from Peachpit Press.
if you have tips or tricks to share, or Mac-related questions you want answered.
Observer Comments
Fri Apr 06, 2007 8:54 am Subject: Rebuild the desktop DB
To Select Volume to boot from during startup...
Press and hold the:
N - NetBoots a Mac. Don't do this if you don't want to NetBoot the computer. It only works in recent Macs.
option key - Will [eventually] take you to a screen where the Mac will display icons of all the bootable drives (not sure if it'll do all bootable partitions, don't think it will though] available on your machine: Hard Drives, iPods, CD/DVD's, even Thumb Drives. You can then click on one of the icons to select the drive you wish to [attempt to] boot from, then click on a "Right Arrow" button to continue the start up process from the drive/volume you selected. There is also a "Recycle" button, in case you plug in an additional drive which didn't show up.
Command [or Cloverleaf] - Option would reboot the desktop on pre OS X versions of Mac OS going back to, gosh, probably back to HFS on Floppy days. Don't know if it has any effect on OS X or not.
Command [Cloverleaf] - Option - A - V : Resets low-level monitor configurations for some older AppleVision monitors
Command [Cloverleaf] - Option - N - V : Resets the non-volatile RAM.
Command [Cloverleaf] - Option - O - F: Boot to Open Firmware, which is a very low level system manager only available on certain Macs (G3s and some later)
It's been AGES since I've used the last three, don't know if they remain useful or not.
This one on the other hand...
Command [Cloverleaf] - Option - shift - delete - [number]: Boot from a partition other than the first one at SCSI ID 0 (or other than the previous system default, on systems without SCSI on the motherboard [If I remember properly]. In systems with SCSI, it starts at the highest SCSI ID and counts down; a number will cause it to consider the corresponding SCSI ID first.
That one hasn't been useful since the switch to FireWire over SCSI. Still if you still use/support/access to a SCSI equipped Mac, it could be useful to know.
I'm sure there are more. To this day I still remember the assembler level code to enter into a Mac [128/512/512e/Plus/SE/Mac II et.al/SE30] to reboot the Mac after hitting the programmer's key:
Type first: SM 0 A9F4 [return]
Then type: G 0 [return]
The first command sets memory position 0 [zero] to A9F4 [which is the reboot command], the second line tells the Mac to execute that instruction. I rescued a Prototype demonstration of a Mac Portable (oh! it'll work on the portable and early PowerBooks which have reset and interrupt buttons too!] back in early 1989 at an Apple Sneak preview held for Educational customers.
My how times have changed!
This was a fun trip down memory lane. Perhaps the original article/post can be updated with the additions posted in comments?
Thanks TMO and all the other responders!
Chuck M.
QuoteGuest wrote:
[snip]
Press and hold the:
[snip]
Command [or Cloverleaf] - Option would reboot the desktop on pre OS X versions of Mac OS going back to, gosh, probably back to HFS on Floppy days. Don't know if it has any effect on OS X or not.
[snip]
Chuck M.
Typo Alert: The passage "would reboot the desktop" should have said "would reBUILD the desktop"
Sorry, that post was one that started out short and just kept on getting longer as I typed [like the song "Alice's Resturant" by Arlo Guthrie!
Chuck M.
Fri Apr 06, 2007 9:59 am Subject: This used to work in the old days to eject the Floppy Drives
With new intel macs, holding down the "D" key at startup when you have the restore disk that came with your machine in the drive, will boot that from that disk's Hardware test mode.
============================================
-=-Ron Evry-=-
Creator of 'Mister Ron's Basement' podcast on iTunes
http://slapcast.com/users/revry
============================================
Another: hold down the LEFT shift key and mouse button when you see the progres bar to prevent automatic login. (That's in Mac Help, right at the top.) This may or may not work with a non-Apple keyboard--you'll have to try it. (It does work with my MacAlly keyboard and Kensington TurboMouse.)
Quotejpfreeman wrote:
Now how can I save this list for future reference?
First, like a good Mac user, open Mac Help by going to the "Help" menu or pressing command-? in the Finder. Most are listed there.
Second, copy and paste from this page to a TextEdit document. Mac Help will also tell you how to copy and paste. (The advantage of that to a PDF is that you can choose what you want to save. It does take a bit longer.)
If you want to save the web page, as is, check your browser's help to see what is available. Some can save as a single archive-type file, others save the HTML page and the relevant images, etc.
We should also note that the timing can be important. For example, holding down the Shift key immediately after the startup tone, but releasing when you see the progress bar boots into Safe Mode. If you press the shift key when you see the progress bar, it just prevents startup items from loading.
Fri Apr 06, 2007 4:05 pm Subject: Use the Source, Luke
Startup key combinations for Intel-based Macs
http://docs.info.apple.com/article.html?artnum=303124
Mac OS X keyboard shortcuts
http://docs.info.apple.com/article.html?artnum=75459
Quoteluomat wrote:
Startup key combinations for Intel-based Macs
http://docs.info.apple.com/article.html?artnum=303124
Mac OS X keyboard shortcuts
http://docs.info.apple.com/article.html?artnum=75459
Even easier, open Mac Help to get the shortcuts relevant to your Mac.
Sun Apr 08, 2007 9:05 pm Subject: Command - V Question
Tue Apr 10, 2007 12:26 am Subject: No apple magic here
This startup thing is one of the places apple has really dropped the ball, IMHO. When windoze starts up, it at least tells you hit f4 or something to change the start up. Mac tells you nothing and makes it really hard to see what the options are. How hard would it be to:
a) have the initial screen say "Press the option key now for options"
b) if you hold down option key it gives a menu of options for starting up.
c) when you do Restart with the option key pressed, it gives you the same menu for what kind of a restart you want.
Then I only gotta remember one damn key.
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