It’s Mac OS X season again and with that is a new version of Mac OS X. In this case it is Mac OS X 10.10, or what is better known as Yosemite. Most people will upgrade their Mac over the top of their existing OS, which is perfectly fine. However, there are times when OS X needs to be installed on a new (blank) hard drive, or, we simply want to perform a “clean install”. When doing this I prefer to use a bootable USB drive instead of a DVD. This is becoming especially convenient as newer Macs don’t have (or need) an internal DVD drive.

Boot directly from a.dmg OS X Installer file - posted in Grub4dos: Many.dmg files are simply sector-by-sector disk images. The Yosemite Installer.dmg file seem to contain only one (Type AF HFS+) partition in the MBR. The PBR of these HFS+ partitions can be booted from using the grub4dos chainloader command, however the HFS+ boot code needs to see a valid Type AF partition in a MBR (a real. Os X Yosemite 10.10.2 Bootable Usb Dmg Files How to Boot from USB Drive You must know the system requirementsof OS X Yosemite before installing it, If your system to capable to run this OS X version 10.10 then Shutdown your Mac, plug the OS X Yosemite Bootable USB into Mac.

For reference, Apple has a page that covers how to create a bootable USB drive with the OS X 10.9 Mavericks installation files, but leaves out a few of the details discussed here. This should also provide is little context around this being a standard process that is supported by Apple. No hackery here.

What is needed

The process is easy and any Mac user who considers themselves to be semi-technical will be capable of creating a bootable USB drive containing the Mac OS X installation files. And, this does not require downloading any third-party tools or paying for extra utilities. Here is what you need.

• A Mac with internet access
• One 8 GB (or larger) USB drive
• The OS X installation file from Apple (i.e.; “Install OS X Yosemite”)

Downloading the OS X installation file

To create a bootable USB drive for OS X, you first need to download the desired operating system setup file from Apple, such as OS X 10.10 Yosemite. You can search for the OS, “OS X Yosemite”, in the App Store (or using this link) to access it in the App Store directly. Once the download completes, you will see the OS X Install window for Yosemite (or other version), but do not proceed with the install; you need quit the install. You just needed the Install OS X Yosemite application, which should now be in the Applications folder on your computer. For Yosemite, the file name will be Yosemite.app.

Creating the bootable USB drive

Here is what you need to do:

1. Connect the USB drive to your Mac. Backup any files that may be stored on it before you proceed because this USB drive will need to be completely reformatted.
2. Format the USB drive, using Disk Utility, as a Mac OS Extended (Journaled) drive, named Yosemite. I suggest not using any spaces to keep a future step simple. This is performed using the Erase tab within the Disk Utility app. Be sure the USB drive does not have multiple partitions (that can happen, so use to the Partition tab to verify and correct this).
3. Open Terminal. This located in the Applications > Utilities folder.
4. The following command is used to make the USB drive bootable as well as copying the necessary OS installation files on the USB drive.A couple quick points to help make sense of the command below. The –volume /volume/YosemiteUSB attribute of the command specifies the target drive, the USB drive in this case. The –applicationpath attribute specifies the OS X source installation file that was downloaded earlier. You will also notice the command (createinstallmedia) used to create the installable USB drive is actually contained with Yosemite.app file that was downloaded.Type (paste) the following command

For Yosemite:

• For El Capitan:

1. To kick off the process, type in your user password when requested.

This process can take upwards of 30 minutes or more without any indication on the screen it is still processing. Even though it may appear to have locked up, put your worries aside and your patience will be rewarded. The time it takes will vary depending on the speed of your Mac and the USB drive write speed.

Sample log

Below is a log of the terminal screen from when I created my bootable USB drive containing the Yosemite OS X installation files.

You should now have a bootable USB drive from which you can boot your Mac and perform a fresh install of the Max OS X operating system.

Want to learn how to create a bootable USB installer for OS X Yosemite?. Here is the complete step by step guide which you can follow on your MAC create the bootable USB disc. We all know that Yosemite OS X is the latest operating system form Apple, which comes with lots of new features and improvement. If you are interested in new OS and want to try it then sign up for the OS X Beta Program here, which will allow them to test the new OS, if selected.

Once you have the installation app for Yosemite (Install OS X 10.10 Developer Preview), don’t install it directly, other wise you will lose the file and can’t make the USB disc. To get started all you nee a *GB or above USB drive, Apple computer with Mac App Store (10.6.8+) and OS X Yosemite installer.

Create OS X Yosemite Bootable USB Drive

Step 1. Insert the USB drive or Disc on youir MAC and run the Disk Utility app from the Applications > Utilities folder.

Step 2. Now in the app select the USB drive and Selct the Partition Tab.

Step 3. Under Partition Layout, select 1 Partition from the drop-down menu. And enter the Partition information Name: ”yosemite”, Format: “Mac OS Extended (Journaled)”.

Step 4. Click the Options... button and Select GUID Partition Table. After that hit the “Ok” button then “Partition” button.

Step 5. Now the partition process will start and this will take some time to format and making USB drive as a 1 partition

Now the USB part is over and lets move to the OS X Yosemite installer package.

Step 6. Go to Applications again and find the Install OS X 10.10 Developer Preview app that you downloaded.

Step 7. Right-click the installer and select Show Package Contents from the context menu. See the Screenshot below:-

Step 8. Now navigate to Contents -> SharedSupport and open InstallESD.dmg

Step 9. This will start the verify process on your MAC. Wait for some time…….

Os X Yosemite 10.10.2 Bootable Usb Dmg Files

Step 10. Once the verify process is done you will see the Package Folder.

Step 11. Don’t do anything with this Packages folder just yet. First, we need to unhide the files located in this newly mounted OS X Install ESD image.

Step 12. Launch Terminal.app to enter a command to unhide the file and folder on your MAC.

Step 13. Enter the below mention two commands one by one:-

defaults write com.apple.finder AppleShowAllFiles TRUE

killall Finder

Step 14. Now you will see three more files next to the Package folder (Step 10)

Step 15. Switch back to Disk Utility.app to select the partition name created in step 3.

Step 16. Now drag the partition from the device list to the Destination box. Also, drag the BaseSystem.dmg to the Source path
Hit the Restore button.

Step 17. Now a new popup screen appears. From here click on Erase to start the restore process, then enter in your admin password and hit OK to proceed.

Step 18. Once the restore process is done, you will see a new window son your screen. Like the screen below:-

Step 19. Here, open the “System” > “Installation” folders and move the Packages file to trash.

Step 20. Now copy the Packages folder from Step 10 and paste it into the Installation folder that you just opened in previous step.

Os X Yosemite 10.10.2 Bootable Usb Dmg File Download

Step 21. Now Hide the system files again using this command on terminal window

defaults write com.apple.finder AppleShowAllFiles NO

Os X Yosemite 10.10.2 Bootable Usb Dmg File Iso

That’s it!. To perform a clean install on your MAC, simply insert the USB drive that you created, power on the computer, and hold down the [option] key to access the boot selection menu. From there, select the USB drive partition, and follow the prompts to install OSX 10.10 on your Mac.