SPEEDY-NUC:clover.git rehabman$ /Applications/Install\ macOS\ High\ Sierra\ Beta.app/Contents/Resources/startosinstall
Usage: startosinstall --applicationpath <install macOS.app path>
Arguments
--applicationpath, a path to copy of the OS installer application to start the install with.
--license, prints the user license agreement only.
--agreetolicense, agree to license the license you printed with --license.
--rebootdelay, how long to delay the reboot at the end of preparing. This delay is in seconds and has a maximum of 300 (5 minutes).
--pidtosignal, Specify a PID to which to send SIGUSR1 upon completion of the prepare phase. To bypass "rebootdelay" send SIGUSR1 back to startosinstall.
--converttoapfs, specify either YES or NO on if you wish to convert to APFS. If you do not specify this, the default is YES.--usage, prints this message.
Example: startosinstall --applicationpath "/Applications/Install macOS.app" --converttoapfs YES