Today I have to re-install my laptop because there is a bug in the grub boot-loader.

I tried the grub-rescue command and this one was really useful to list the file systems, etc...

But I didn’t have time to find the documentation on internet, so, first solution, re-install Ubuntu.

Here is the original link for this documentation: http://www.ubuntu.com/download/help/create-a-usb-stick-on-mac-osx

In a terminal

  1. Download the Ubuntu ISO:

    wget ftp://ftp.belnet.be/pub/ubuntu.com/releases/12.10/ubuntu-12.10-desktop-amd64.iso

  2. Convert the iso file to img using the convert option of hdiutil:

    hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/ubuntu.iso

  3. Run diskutil list to get the current list of devices:

    diskutil list

  4. Insert your flash media and run diskutil list agin and determine the device node assigned to your flash media (e.g. /dev/disk2).

  5. Unmount the disk (in my case, the flash media was mapped on /dev/disk2) :

    diskutil unmountDisk /dev/disk2

  6. Copy the .img file to the flash media:

    sudo dd if=/path/to/target.img of=/dev/rdisk2 bs=1m

  7. Eject the flash media:

    diskutil eject /dev/disk2

  8. Restart and boot with your USB stick.

Of course, these instructions will work fine with an other distribibution.