This is the simplest method, which will install macOS Big Sur over your current macOS version, keeping your files and apps intact.
To boot an Intel Mac from this drive, hold down the key immediately upon restarting. For Apple Silicon Macs (M1/M2), shut down the device, then press and hold the Power button until the startup options screen appears. If you run into issues creating the image, let me know: What model and year is the Mac you are currently using? What macOS version is it running right now? What specific error message or behavior did you encounter?
Select your internal hard drive (usually labeled Macintosh HD). Click the icon at the top of the interface.
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume macos big sur 1121 installer dmg
Here is a proposed feature for the DMG:
If build 11.2.1 is available in the fetch tree, target it specifically by typing: softwareupdate --fetch-full-installer --full-installer-version 11.2.1
System administrators often require raw DMG files rather than standard App Store installers. A DMG container allows IT staff to deploy operating systems across multiple corporate machines using Mobile Device Management (MDM) tools. Additionally, standalone DMG files are vital for configuring macOS environments inside virtualization software like VMware Fusion, Parallels Desktop, or VirtualBox. Technical Specifications and Compatibility This is the simplest method, which will install
: Includes important security updates, most notably addressing a major vulnerability in Stability Improvements
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/BigSur --nointeraction Use code with caution. Detach the newly written volume: hdiutil detach /Volumes/Install\ macOS\ Big\ Sur Use code with caution.
Use Apple's built-in creation tool hidden inside the downloaded application package to populate your blank disk image. (Note: This step requires administrator privileges; you will need to type your Mac user password). If you run into issues creating the image,
: Reinstall the OS if your Mac experiences system corruption or cannot boot.
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyUSB