How to create a bootable USB flash drive for installing macOS Sierra
macOS Sierra (version 10.12) - an operating system for personal computers and servers, developed by Apple; the thirteenth version of macOS. It was announced on June 13, 2016 at the WWDC 2016 conference. The public release of the OS took place on September 20, 2016.
macOS Sierra was announced on June 13, 2016 at WWDC 2016. The focus of updates in this version of OS X is on Continuity, iCloud, and upgrading the basics of the Mac environment. Anyone who is eager to take a look at the new macOS can install it now. We tell you how to make a clean installation using a USB flash drive and how to roll back to OS X El Capitan if something goes wrong.
There are two ways: updating from the current OS and a clean installation using a boot disk . We recommend that you always install new versions from scratch, and then roll back the backup you made earlier on all the necessary data so as not to drag old problems into the new system.
Before you begin, be sure to make a backup of Time Machine, which will help you quickly restore your Mac if you want to return everything as it was. We will need the installation image, a blank USB flash drive (at least 8 GB) and a compatible Mac. The image can be downloaded officially or from torrents, you probably have a flash drive, like a Mac. Let's get started!
MacOS Sierra supports MacBook Pro (from 2010), MacBook Air (from 2010), Mac mini (from 2010), Mac Pro (from 2010), MacBook (from 2009), iMac (from 2009).
First, make sure your MacBook meets the stated specifications!
How to create a bootable USB flash driveone
Open the macOS Sierra image and copy the Install 10.12 Developer Preview.app file from it into your applications (if you downloaded it from the Internet) or simply download the macOS Sierra installer from the AppStore into the program.2
Connect your USB flash drive to the Mac (remember, all data from the USB flash drive will be deleted).
Rename it to SierraInstaller.four
Open “Terminal”, copy the following command and confirm the execution by entering the administrator password:
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/SierraInstaller --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction &&say Done5
The process of creating a boot disk will begin, which will take about 15 minutes.
Erasing Disk: 0%... 10%... 20%... 30%...100%... Copying installer files to disk... Copy complete. Making disk bootable... Copying boot files... Copy complete. Done.6
Upon completion, you will see (and hear) confirmation that everything went well. Your bootable flash drive is ready!
Now it remains to restart the Mac, while holding down the Option key, select the macOS Sierra flash drive in the list of bootable disks and follow the prompts of the installation wizard.
Just in case: How to roll back to OS X El Capitan
The programs you need do not work, errors endlessly crash, or have you just satisfied your curiosity and want to return everything back? There is nothing easier.
To do this, we will need a bootable USB flash drive - as you probably already guessed - with OS X El Capitan.
Well, then - the same principle as when installing any version of OS X: boot with the Option key held down and the USB flash drive connected, select it in the list and follow the prompts of the installation wizard.
Via lifehacker.ru & wiki