When you get a new Mac, it might be a good idea to do a clean installation; starting from scratch, with a brand-new operating system, and copy the files that you need from your old Mac manually. Here’s how to migrate your files to your new Mac, or do a clean installation, and the pros and cons of both methods.
Proceed with reinstalling OS X. Note that the Snow Leopard installer will not erase your drive or disturb your files. After installing a fresh copy of OS X the installer will move your Home folder, third-party applications, support items, and network preferences into the newly installed system. Download and install Mac OS X 10.6.8 Update Combo.
Check for Mac OS Problems Next. Now, for the first step of software diagnostics. The view that I take is that after assuring that hardware conflicts aren’t the answer, determining whether the machine has OS problems, or simply applications problems, is the next step. Address Likely Corrupt Preferences.
Shut down your Mac, turn it on while holding down Command+R. Your Mac will boot into the recovery partition. If you’re using an older Mac (from 2010 or earlier), there’s a chance that you can’t use Recovery Mode. On those devices, hold “Option” while turning your computer on, then select the recovery partition instead.
Start up from macOS Recovery
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
Apple silicon
Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
Intel processor
Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.
If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.
Now And Then (his Highness 1) Mac Os Catalina
Reinstall macOS
Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions.
Follow these guidelines during installation:
If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.
Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
After installation is complete, your Mac might restart to a setup assistant. If you're selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.
Other macOS installation options
When you install macOS from Recovery, you get the current version of the most recently installed macOS, with some exceptions:
On an Intel-based Mac: If you use Shift-Option-Command-R during startup, you're offered the macOS that came with your Mac, or the closest version still available. If you use Option-Command-R during startup, in most cases you're offered the latest macOS that is compatible with your Mac. Otherwise you're offered the macOS that came with your Mac, or the closest version still available.
If the Mac logic board was just replaced, you may be offered only the latest macOS that is compatible with your Mac. If you just erased your entire startup disk, you may be offered only the macOS that came with your Mac, or the closest version still available.
You can also use these methods to install macOS, if the macOS is compatible with your Mac:
Now And Then (his Highness 1) Mac Os Update
Use the App Store to download and install the latest macOS.
Use the App Store or a web browser to download and install an earlier macOS.
Use a USB flash drive or other secondary volume to create a bootable installer.
Now And Then (his Highness 1) Mac Os Pro
While away from Apple and working for NeXT, yet another computer company he founded, Jobs picked up a few new tricks — one very important trick in particular: the operating system that would become Mac OS X ('ten' not the letter X). Released in March 2001, and touted as virtually crash-proof, OS X was also easy on the eyes because of its 'aqua' look and feel, noted for its soft edges, translucent colors and pinstripes. OS X continued to evolve, going through nine different iterations in ensuing years; its stability, speed and ease of use became a major selling point for new Mac users who switched from Windows-driven PCs.