bootable usb Big Sur reateinstallmedia: invalid option -- ?

See this page for the correct Terminal commands…

How to create a bootable installer for macOS - Apple Support

Creating a USB Installer is predicated on the Full Version of the Installer ( High Sierra ) is located in the Applications folder of the computer

Have used this command several times and it has worked just fine

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ High\ Sierra.app --nointeraction

Where the Untitled " in above command " is the Name Given the 16 GB Capacity Drive when formatted as HFS + ( Journaled ) with GUID Scheme Partition Map

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Since the error is "invalid option" I suspect you do have the full installer, but somehow the option is not correct. Is there at least one space after the command "createinstallmedia"? And a double hyphen (dash) preceding "volume"? Even when I copy & paste this into a code block the one hyphen in the "--volumes" looks wrong. The second dash looks longer which may be due to the forum editing window, or it may be the actual problem, but the double hyphen for the next option "--applicationpath" looks normal. Or is "--applicationpath" being considered part of the path to your USB stick because there isn't a separating space?

I always use this command sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

And make sure to name your USB drive to MyVolume, that way you can just copy/paste the command in a terminal window.

Hope this helps

The reason for the error is that command is using conflicting locations for the installer app. Apparently, /Applications/Install\ macOS\ High\ Sierra.app/ does not exist.

In the following I am assuming your downloaded High Sierra installer app is located in ~/Downloads instead.

(the path are get dragging the icons from the finder to the terminal)

You're on the right track, but the second pathname does not exist. It would be correct if you drag the High Sierra installer app icon (which I assume resides in ~/Downloads) to just past applicationpath.

Try this:

sudo /Users/noidue/Downloads/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/chiavetta --applicationpath /Users/noidue/Downloads/Install\ macOS\ High\ Sierra.app

That should work.

Good observation!