Mac Sage

I recently encountered a Mac that would not boot properly. However, it did boot into single-user mode and allowed access to the file system via the command line interface. Since I had recently purchased an external, portable USB drive, I wanted to offload my important files to the USB drive before reformatting and reinstalling a fresh system. Here are the steps I took:

• Connect USB drive to Mac and boot into single-user mode (cmd-s)
• At prompt type:

  /sbin/mount -uw /

  then hit return

• At prompt type:

  /sbin/fsck -fy

  then hit return

• At prompt type:

  ls /Volumes

  then hit return. This should provide a list of mounted volumes. It’s likely that your USB drive will not show. If this is true, then you will need to create a sharepoint in the /Volumes directory. You do this by using this command (in this case, we are creating a directory called “usb”):

  mkdir /Volumes/usb

  then hit return

• Next we need to identify the disk number of the USB drive. This is done with this command:

  ls /dev/disk*

  then hit return. The system will list the disks like this:

  

  In most cases, the USB drive will be the last disk number listed (in this case: disk0s3).

• Now, to mount this disk to your sharepoint, type the following command:

  /sbin/mount_msdos /dev/disk0s3 /Volumes/usb

  then hit return. NOTE: In this case, we are using disk0s3 since it is the last listed. Yours will likely be different. Also note that my Western Digital USB drive uses the msdos format. Yours may not.

• If this is mounted properly, you will be able to see the contents of your USB drive by using this command:

  ls /Volumes/usb

  then hit return

• If you have successfully mounted the USB drive, you may now copy files using the cp command. (In this example, I will copy a file named “testfile” and assume the Mac has a volume named MacHardDrive.) For example:

  cp /Volumes/MacHardDrive/testfile /Volumes/usb/

  then hit return.

You can use this method to copy entire directories from your ailing Mac to the USB drive. In my case, I copied the entire user account directory over to the USB drive so I would keep settings, mail, music, pictures, and files in my Documents directory.

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I’ve been doing some troubleshooting lately and find this list of startup key commands very helpful:

Mac

• X during startup – Force Mac OS X startup
• option – (eventually) brings up a screen with startup volume choices
• Option-Command-Shift-Delete – Bypass primary startup volume and seek a different startup volume (such as a CD or external disk)
• C – Start up from a CD that has a system folder
• N – Attempt to start up from a compatible network server (NetBoot)
• T – Start up in FireWire Target Disk mode (very handy for plugging your Mac into another as an external hard drive)
• Shift – start up in Safe Boot mode and temporarily disable login items and non-essential kernel extension files (Mac OS X 10.2 and later)
• Command-V – Start up in Verbose mode.
• Command-S – Start up in Single-User mode
• cmd-opt-p-r – Zap PRAM. Hold down until second chime.
• cmd-opt-n-v – Clear NV RAM. Similar to reset-all in Open Firmware.
• cmd-opt-o-f – Boot into open firmware
• hold mouse click – force eject a CD/DVD

Mac Intel

• Press C during startup Start up from a bootable CD or DVD, such as the Mac OS X Install disc that came with the computer.
• Press D during startup Start up in Apple Hardware Test (AHT), if the Install DVD 1 is in the computer.
• Press Option-Command-P-R until you hear two beeps. Reset NVRAM
• Press Option during startup Starts into Startup Manager, where you can select a Mac OS X volume to start from. Note: Press N to make the the first bootable Network volume appear as well.
• Press Eject, F12, or hold the mouse button Ejects any removable media, such as an optical disc.
• Press N during startup Attempt to start up from a compatible network server (NetBoot).
• Press T during startup Start up in FireWire Target Disk mode.
• Press Shift during startup Start up in Safe Boot mode and temporarily disable login items.
• Press Command-V during startup Start up in Verbose mode.
• Press Command-S during startup Start up in Single-User mode.
• Press Option-N during startup Start from a NetBoot server using the default boot image.

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