How to create a bootable USB flash drive to install macOS Sierra
macOS Sierra (version 10.12) - an operating system for personal computers and servers developed by Apple; the thirteenth version of macOS. Announced on June 13, 2016 at the WWDC 2016 conference. The OS public release took place on September 20, 2016.
macOS Sierra was announced on June 13, 2016 at WWDC 2016. The focus of the updates in this version of OS X is on Continuity, iCloud, and upgrades to the basics of the Mac computers. Anyone who can't wait to see the new macOS can install it now. We tell how to make a clean installation using a flash drive and how to roll back to OS X El Capitan, if something goes wrong.
There are two ways: upgrade from the current OS and clean install using a boot disk . We recommend that you always install new versions from a clean slate, and then roll back previously made backup of all the necessary data so as not to drag the old problems into the new system.
Before you begin, be sure to make a backup copy of Time Machine, which will help you to quickly restore your Mac if you want to return everything as it was. We need an installation image, a clean 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. Getting 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 complies with 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.2
Connect your USB flash drive to your Mac (remember, all data from the USB flash drive will be deleted).
Rename it to SierraInstaller.four
Open the "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, which takes about 15 minutes, will begin.
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 USB flash drive is ready!
Now it remains to restart the Mac, hold down the Option key, select the USB flash drive with macOS Sierra from the list of boot 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 fly out, or have you just already satisfied your curiosity and want to return everything back? There is nothing easier.
To do this, we 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 up with the Option key and the connected USB flash drive pressed, select it in the list and follow the prompts of the installation wizard.
Via lifehacker.ru & wiki