Bootable installer for macOS
It is now time for my yearly OS software update for my MacBook. Rather than leaving things to the automated process of the installer to overwrite my existing OS, I always prefer to do a clean install and create a bootable thumb drive.
Always having a bootable drive handy is another way of insuring I can take full advanatage of the built in diagnostic tools in the OS to resolve any hardware or firmware issues. While performing a clean install every year is a definitive way to make sure I have my MacBook runing at optimal performance and also makes it feel like new again!
Wiping the HD clean and installing the new OS also eliminates any issues one might incur from the more automated installer process of overwriting your current OS with the new one.
However for most developers the main draw back of doing a clean install is having to setup your MacBook from scratch with such things as re-installing any command line packages and reconfiguring any modifications you may have made to your Host file or local Apache server files.
• Download the new macOS installer:
You can get the latest version of macOS from the Apple Developer portal download section. Your download may redirect you to the Mac App Store. If so you will find that the installer will download it to the /Applications folder. Be sure to quit the installer if it automaticaly launches.
• Make bootable drive with ‘createinstallmedia’ Terminal command
Get a dedicated USB key with around 8GB of free space. Connect to your Mac and launch terminal. As per Apple instructions here:
With OS X El Capitan, Yosemite, or Mavericks, you can use a USB flash drive or other removable media as a startup disk…support.apple.com
you can access the createinstallmedia command via typing the appropriate path to your macOS download.
eg: path for macOS Sierra
/Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia
an example of the full terminal commmand would look something like the below :
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/<<yourUSBDriveName>> --applicationpath /Applications/Install\ macOS\ Sierra.app
(<<yourUSBDriveName>> would be replaced by the name of your USB drive)
When you run the command you will be promted for your password and to type Y to continue
Then you are done.
To boot up from your USB Drive simply restart your mac and hold down the “option” key. You will be presented with the option to select which drive you wish to boot from. From here you can launch Disk Utility and wipe your HD for a clean install.