Install OS X 10.10 Yosemite

You can install OS X to a choice of media, such as USB drive, SD Card or an external hard drive connected via USB 2.0, USB 3.0, FireWire or Thunderbolt.

It is possible, theoretically, to run OS X from any of these different types of media though–practically speaking–it is probably best to choose USB 3.0 or Thunderbolt. This is down to the transfer speeds possible. With USB 2.0 the experience is quite slow.

You should also note that it is not normally possible to install a version of OS X prior to the version that originally shipped with the particular Mac that you are using.  For example, if the Mac originally shipped with OS X 10.8 Mountain Lion, then it is not normally possible to install OS X 10.7 Lion.

Whilst the OS X installers are much smaller, you will need to factor in approximately 10GB for the installed version of OS X. If you are using aUSB Flash Drive, or an SD Card, it will need to be 16GB or greater in capacity.

For the best possible experience, I’d recommend using this technique in the following circumstances:

  • Testing a later version of OS X to the one you are running on the Mac
  • Using USB 3.0 or Thunderbolt external drive, or
  • Using USB flash drive (16GB or greater)

I do not particuarly recommend using an SD Card or a USB 2.0 external drive.  They’ll work, but they are quite slow.

The process for installing OS X on an external volume is quite straight-forward. Essentially, it’s just the downloading of the particular OS X installer required, the correctly formatting of an external volume and the installation of OS X.

Connect an external drive
  • Connect an external drive to the Mac.  In this example the drive is a 1TB USB 3.0 external hard drive that is preformatted in the Microsoft File Allocation Table (FAT) format.
Partitioning, naming and formatting the external hard drive
  • Select the hard drive in the left hand pane, as shown, and click thePartition tab
  • Ensure that 1 Partition is selected int he Partition Layout field
  • If you wish, name the drive in the Name field
  • Select the Options… button
Ensuring that the external drive is correctly formatted
  • Select GUID Partition Table to allow the external drive to be used as a startup volume with a Mac.
Confirming the partitioning, and formatting, of the external volume

Check the confirmation dialogue box and, if in agreement with the proposed action, click Partition to format the external volume.

Downloading an OS X installer from the Mac App Store

Open the Mac App Store application and navigate to the Purchasespane. Provided that you have previously purchased them, you should seeLion and/or Mountain Lion, though they may show as Installed.  Note, Yosemite is only available to registered Apple developers at the time or writing, so you’ll not see this option in the Mac App Store.

To download the installer, hold down the Option key and click thePurchases tab.  The button to the right of the app should change toInstall.

Use Spotlight to find OS X Installers that are already on the Mac

If that does not work, search for the installer on the Mac, as it may already have been downloaded.  Open Spotlight and type Install OS X to find the required installer.

This example shows how to install OS X 10.10 Yosemite, though the procedure remains the same for OS X 10.7 Lion, 10.8 Mountain Lion and 10.9 Mavericks.

Launch the OS X installer

Launch the OS X installer that was downloaded from Mac App Store. The installer is normally located in the Applications folder.

You may have found it, instead, using Spotlight.

Read the terms and conditions.  You’ll need to Agree to them in order to continue with the installation.

Click the button Show All Disks…

Be aware that only the hard drive in the Mac will be shown by default. Click the button that says Show All Disks… to reveal other volumes that are attached to the Mac.

Select the appropriate external volume onto which OS X is to be installed

Select the external volume to which you’d like to install the operating system.  In this example, I am installing OS X 10.10 Yosemite to the external volume Yosemite 1TB from a Mac that is running OS X 10.8 Mountain Lion.

Installing OS X to the external drive volume

A progress bar will indicate the status of the installation of the software to the external volume.

Click the Restart button to restart the Mac, or wait 30 seconds for a restart

The Mac will then count down from 30 seconds before restarting unless you click the Restart button within this timeframe.

The Mac will then restart

The Mac will then restart and finish the installation process on the external hard drive.

When the Mac restarts, it will reboot into the version of OS X that you’ve installed to the external volume.  In my example, it’s OS X 10.10 Yosemite.

When you boot the Mac, listen out for the startup chime.  Immediately after the chime sounds, press and hold down the Option key (sometimes marked Alt).

After a short time, you will be presented with a screen similar to the one shown above.  Use the left and right arrow keys to navigate to the external volume, in my example an external 1TB USB 3.0 drive, and pressEnter.

Navigating to Apple > System Preferences > Startup Disk

If you are currently using your Mac and wish to reboot to a different volume, open up System Preferences by clicking on the Apple on the lefthand side of the menu bar.

Select the appropriate startup disk into which to boot next time the Mac is turned on

Select Startup Disk then choose which volume from which you wish to boot you restart the Mac.

Startup Key Combinations

Startup key combinations are invoked immediately following the startup chime, and before the grey Apple logo appears in the middle of the screen, when you power-on your Mac.

The object of these key combinations is to perform different functions, many of which are useful in the maintenance of Macs. The key combinations listed in this tutorial are specifically for use with Macs with Intel processors.

Tip: If you have a Windows keyboard, you can usually use the Windows key as the substitute for the Command key on the Mac keyboard.

Tip: If you are having difficulty invoking startup key combinations, ensure that you press and hold the keys immediately after the startup chime. Alternatively, use a wired keyboard where possible, to rule out any issues possible with Bluetooth keyboards.


Pressing the C key immediately after the startup chime will enable the option to boot from a range of media such as a bootable CD, bootable DVD or a bootable USB drive. This might include OS X install media (up to OS X 10.7 Lion) or USB install drives that you have created for other versions of OS X.


Pressing the D key immediately after the startup chime will boot your Mac into a suite of diagnostic utilities that enable you to test the hardware of your Mac. This is a useful way to rule out any hardware issues when trying to diagnose a possible problem with your Mac (which is why you may not have heard of it and, no doubt, have never used it!)

Tip: Remember D for Diagnostics.


This one is a bit of a finger-twister and, unless you are more dextrous than I, you’ll need both hands. The PRAM, on PowerPC Macs, or NVRAM, as it is on Intel Macs, is the non-volatile (random access) memory that stores various information about your Mac. This information includes:

  • speaker volume
  • screen resolution
  • startup disk selection
  • recent kernel panic information, if any

Resetting the NVRAM, on Intel Macs, may be one way of solving an issue related to the above areas.

When you invoke the Command-Option-P-R keyboard combination, keep the keys held down immediately after the first startup chime and release them upon hearing the second startup chime.


Pressing the Option key immediately after the startup chime will show you the available startup volumes.

A startup volume is a hard drive, USB drive, CD or DVD that contains a usable operating system from which the Mac can be booted.

This is particularly useful if you have your hard drive partitioned with two (or more) operating systems from which you wish to boot your Mac. Or, in the case of maintenance and recovery, when you need to boot from an external drive.


Pressing the Eject or F12 keys immediately after the startup chime will eject any removable media, such as an optical disc.

This is a useful option on those occasions when you just don’t seem to be able to get OS X to eject a DVD from the SuperDrive.

That said, the reliance on optical media is diminishing now that modern Macs are supplied without a SuperDrive.


Pressing the N key immediately after the startup chime will allow you to boot the Mac from a compatible network server. This option is most likely to be used by businesses with a network of Macs.


Pressing the T key immediately after the startup chime will allow another Mac with a FireWire port (the target Mac) to be used as an external hard drive connected to another Mac (the host).

Target Disk Mode is useful for accessing the contents of a Mac which cannot be booted from its own hard drive.


Pressing the Shift key immediately after the startup chime will start up your Mac in a way that performs particular checks and prevents certain software from automatically loading or opening.

This is particularly useful if any maintenance is required on your Mac and can be used to resolve or isolate certain problems that exist on the internal hard drive (startup volume).


Pressing the Command-V keys immediately after the startup chime will start up your Mac in verbose mode. Verbose mode is typically used for troubleshooting; it shows what is happening during system startup.

It is possible to start in verbose mode every time you start your Mac, by opening Terminal and entering the following command:

sudo nvram boot-args="-v&"

To disable verbose mode booting, enter:

sudo nvram boot-args=

If you just want to boot into verbose mode on an ad-hoc basis simply hold the Command-V keys.


Pressing the Command-S keys immediately after the startup chime will start up your Mac in single-user mode.

Single-user mode is a mode in which a multiuser OS X operating system boots into a single superuser for the purposes of maintenance.


Pressing the Option-N keys immediately after the startup chime will start up your Mac from a NetBoot server using the default boot image. This is of most use to businesses with a network of Macs.


Pressing the Command-R keys immediately after the startup chime will start up from the OS X Recovery System.

The OS X Recovery System is available with all Macs that originally shipped with OS X 10.7 Lion onwards. That said, the following Macs may require the download and installation of updated EFI Firmware for these computers to use the OS X Internet Recovery feature:

  • MacBook Pro (13-inch, Early 2011)
  • MacBook Pro (15-inch, Early 2011)
  • MacBook Pro (17-inch, Early 2011)
  • iMac (21.5-inch, Mid 2011)
  • iMac (27-inch, Mid 2011)
  • MacBook (13-inch, Mid 2010)
  • MacBook Pro (13-inch, Mid 2010)
  • Mac mini (Mid 2010)
  • MacBook Pro (15-inch and 17-inch, Mid 2010)
  • iMac (21.5-inch and 27-inch, Mid 2010)
  • MacBook Air (11-inch and 13-inch, Late 2010)

The OS X Internet Recovery System allows you to start your Mac directly from Apple’s servers. Starting up in this way performs a quick test of your Mac’s memory and hard drive to check for hardware issues. OS X Internet Recovery can download and start from a Recovery System image before you are offered the same utilities and options as a local Recovery System.

Customizing the Mac OS X Dock

Here are some handy Terminal tricks for making the Dock your own.


OS X Terminal App

All of these customization options rely on Terminal commands. Terminal is an application included in OS X that allows the user to, among other things, access and modify low-level settings in the operating system.

Terminal can be found in Applications > Utilities. You can either type the commands below directly into Terminal or copy and paste them. All commands are case sensitive. After entering each command press “Return” to submit it.

Because we’ll be modifying files that are in active use on the system, the changes won’t take place immediately.

Therefore, after entering each command, type the following and press Return to quickly restart the Dock:

killall Dock

The Dock will disappear briefly and then reload with the changes now visible.

Enable 2D Dock Mode

For the first few years of its life, the OS X dock was a 2D row of icons that displayed applications, utilities, and folders. Starting with the release of OS X 10.5 Leopard in 2007, however, Apple changed the dock to feature a “3D” look, with the icons now resting on a 3D platform. Functionality generally remained the same, but many users prefer the 2D look over the 3D look.

2D Dock in OS X Pre-Leopard

To change the Dock back to “2D Mode,” enter the following Terminal command and press Return:

defaults write no-glass -boolean YES

After pressing Return, remember to type “killall Dock” (see above) to force the change to take effect.

The 3D Default Dock in OS X 10.8 Mountain Lion

Although the 2D Dock looks a bit different than its predecessors in earlier versions of OS X, the change still gives user the general look they were missing. If you don’t like the new look and want to change back to the default 3D Dock, simply retype the Terminal commands above and replace “YES” at the end with “NO” (again, remember to type “killall Dock” afterwards to force the change to take effect).

The 2D Dock in 10.8 Mountain Lion

Show Only Active Applications

By default, OS X’s Dock displays all active applications as well as inactive applications and folders that the user wants to keep handy. Some users, however, may wish to limit the Dock to displaying only open and active applications. To do this, head back to Terminal and enter the following command:

defaults write static-only -bool TRUE

Once the change takes effect, you’ll notice that your Dock is likely much smaller now, with only open applications displayed. In the following screenshots, the first image shows the Dock before entering the Terminal command. Finder, Mail, TweetBot, Safari, Pages, Activity Monitor, and Terminal are open, but all the other applications are still displayed.

Standard Dock Showing All Active and Inactive Items

After entering the Terminal command the Dock is much smaller, and only those open applications are displayed. This option is great for users who wish to use the Dock primarily as a tool for managing open applications while using another means, such as Spotlight, to actually launch applications.

OS X Dock Displaying Only Active Applications

To reverse the change, retype the Terminal command and replace “TRUE” with “FALSE”.

Change the Maximum Magnification Level

One of the “eye candy” features of OS X’s Dock is the Magnification option. This allows users to keep their Dock size very small while still being able to easily see and select applications when needed. Apple includes a slider to choose how big the “magnified” icons become with a default maximum of 128 pixels, but users can override that arbitrary maximum and set their own limit.

Default OS X Dock Magnification 128 Pixels

Return to Terminal and enter the following command:

defaults write largesize -float 256

This will set the maximum to 256 pixels, as seen in the screenshot below.

Dock Magnification Set to 256 Pixels

You can also go nuts and set it even larger, to 512 pixels:

Dock Magnification Set to 512 Pixels

To reset the magnification level to the default size, enter this command:

defaults write largesize -float 128

Granted, the usefulness of this command is limited but it is presented in the spirit of total customization.

Change the Dock’s Position

By default, the Dock sits centered in the middle of the screen. While you can’t move it to any arbitrary location, the following terminal commands allow you to pin the Dock to either then left or right side of the screen.

To position the Dock on the left side of the screen:

defaults write pinning -string start

OS X Dock Pinned to Left Side of Screen

To position it on the right side of the screen:

defaults write pinning -string end

OS X Dock Pinned to Right Side of Screen

To return the Dock to the default middle location:

defaults write pinning -string middle

OS X Dock Pinned to Center of Screen

Note that this also works if you have your dock pinned vertically to the right or left of the screen using System Preferences > Dock > Position on Screen. In this configuration, “start” aligns the dock at the top of the screen while “end” places it at the bottom.

Dim Hidden App Icons

A useful feature of OS X’s window management is the ability to hide apps (Command-H). This leaves the app’s icon open in the Dock, but completely hides all of the app’s windows. By default, however, there is no indication via the Dock as to which apps are actually hidden compared to those with closed windows or windows that are buried underneath other applications.

Hidden Apps on the Dock

To change this, enter the following Terminal command, which will dim the icons of hidden applications:

defaults write showhidden -bool true

In the second screenshot, below, Safari and Terminal are hidden after implementing this feature, and their icons are dimmed compared to the default setting. This allows users to easily see which apps are hidden without compromising the usefulness of the Dock. It’s frankly puzzling why Apple doesn’t enable this feature by default.

Dim Hidden Dock Icons

Use the Hidden “Suck” Animation to Minimize Windows

Users have two default options for the effect used when a window is minimized to the Dock: Scale and Genie. “Scale” does what its name implies and simply shrinks the application window down into the dock when minimized. “Genie” is a bit more interesting and distorts the window as it minimizes by pulling both bottom corners simultaneously.

Default Genie Animation OS X Dock

A hidden animation, “Suck,” can also be implemented with the following Terminal command:

defaults write mineffect suck

This animation also distorts the window but appears to pull primarily from the bottom-right corner of the window. This results in a more interesting distortion of the window as it shrinks to the Dock, as if the window were indeed being “sucked” down from the bottom-right corner.

Hidden Suck Animation Dock OS X

To change the animation style again, you can reenter the command with “genie” or “scale” instead of “suck.” You can also change it by going to System Preferences > Dock > Minimize Window Using… and choose one of the default options.

Always Show Full Trash Icon

OS X’s Trash, like the Recycle Bin in Windows, has a dynamic icon that changes depending on its status. When there are no items in the Trash, the icon displays an empty trash can. When the user deletes an item, the icon immediately changes to show a trash can filled with paper.

In most situations, this is a useful visual indicator that something is in the Trash. For those who like a static icon, however, enter the following Terminal command to force the Trash to always display a full icon, even if there are no files inside:

defaults write trash-full -bool YES

Always Show OS X Dock Trash Icon Full

After the change has take effect, you’ll notice that the Trash icon always looks full, regardless of whether any files are actually in the trash. To reverse the change, simply reenter the command and replace “YES” with “NO”.

Add a Recent Items Stack

Enter the following Terminal command to create a special stack on the right side of the Dock that contains recently-accessed items:

defaults write persistent-others -array-add '{ "tile-data" = { "list-type" = 1; }; "tile-type" = "recents-tile"; }'

After it has been created, right-click (Control-click) on the stack to change its options. Users can choose to display the most recent Applications, Documents, or Servers, or user-defined favorite Servers and Items. You can also customize how the stack is displayed.

Recent Items Stack

To get rid of the stack, simply right-click on it and choose “Remove from Dock.”

Add Spacers to the Dock

The OS X Dock by default contains a single non-modifiable spacer between the applications portion on the left and the file, folder, and Trash portion on the right. Using the Terminal command below, however, users can add additional spacers to the Dock to help further organize and separate Dock items.

Open Terminal and enter the following command:

defaults write persistent-apps -array-add '{"tile-type"="spacer-tile";}'

Once enabled, you’ll see a blank space appear on the right side of your Dock. Clicking on this space does nothing, but it can be dragged around the Dock like any other item.

Add Space to OS X Dock

Users can add multiple spaces by entering the Terminal command repeatedly. In the screenshot below, four spacers have been added and used to group Dock icons based on task (typing, communication, system tools, etc.).

Multiple Spaces Add to OS X Dock

To remove a spacer, simply drag it off the Dock or right-click on it and choose “Remove from Dock.”