Make a Mac-Bootable USB

An alternative to using Apple’s Superdrive would be a bootable USB drive, as created with the following directions for Apple’s OS-X.

Prepare bootable USB image

  1. Select Launchpad ‣ Other ‣ Terminal to open a terminal.

  2. Convert the downloaded {linux.iso} to a mac disk image with the command:

    hdiutil convert -format UDRW -o ~/Documents/{linux} ~/Downloads/{linux.iso}


For the terminal phobic, the following instructions could replace the preceding command:

  1. Open a Finder window, and display the Downloads folder.
  2. Right-Click the {linux.iso} image file, and choose Open With ‣ Disk Utility.
  3. In Disk Utility, Right-Click the {linux.iso} file and choose Convert ``{linux_.iso}``.
  4. In the Convert dialog, use the default name and location Documents, and click Save to write. {linux.dmg} (The .dmg extension is added automatically.)

Copy Linux image to USB


Throughout these instructions, replace the expression /dev/diskN with the actual identifier of the USB device, e.g., /dev/disk2.

  1. Insert the USB flash media

  2. To get the current list of disk devices, open a terminal from Launchpad ‣ Other ‣ Terminal and run the command:

    diskutil list
  3. Find the device node assigned to the USB media (e.g. /dev/diskN), which should be last listed device

  4. Unmount the USB drive (where N is the disk number) with the command:

    diskutil unmountDisk /dev/diskN
  5. Copy the disk image to the USB device (again N is the disk number):

    sudo dd if=~/Documents/{linux.dmg} of=/dev/diskN bs=1m


    1. The error “dd: Invalid number ‘1m’” will appear on Linux. The correct entries are bs=1M on Linux and bs=1m on OS X.
    2. The error “dd: /dev/diskN: Resource busy” will appear if the USB drive was not unmounted in step 3.
  6. Eject the USB device before removing it with the command:

    diskutil eject /dev/diskN

Install Zentyal from USB

These instructions supplement Installation Instructions to clarify using a USB drive instead of a DVD for Zentyal installation.


These instructions create a multi-boot machine based on the Mac mini Server. Please refer to separate Zentyal server installation instructions for a detailed procedure specific to that operating system.

  1. Restart the Mac, holding down the alt/option key to choose the boot device, either the USB drive or the Superdrive.
  2. Choose the boot media, which Apple humorously refers to as “Windows”.
  3. Boot the Linux installation, select the installation language, and then choose to install by (expert mode).
  4. Use manual partitioning option, and in the free space created previously, first create a 16 Gb swap partition and then an install partition of type ext4 mounted as /.
  5. Continue with Linux installation in the newly-created partitions.
  6. Reboot when installation is finished, removing the USB flash drive or media. The rEFInd boot selector should now contain options to boot Linux.


Either Linux will ask for a location to install the Grub boot loader, or a boot loader installation error will be thrown at the end of the install. Grub is not needed if we are using rEFInd to manage booting.