I have tried this last night
I have cut/pasted all those control lines into Terminal.
I did not know exactly what to do when it asked me for a password at the end.
I typed my Mac password and hit return.
I then booted from the NVMeBoot USB-stick, the Mac booted up into the black screen with a lot of text where I spotted some (I think) errors.
After boot my MacPro 2009 (5,1) now indicated Startup disk in "about this Mac" and in the "System Preferences"
I left my Mac on overnight. This morning I found that it had restarted because an error had occurred and it had restarted back to the old startup disk.
I have tried everything again with the same result.
Here is my com.apple.Boot.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "
http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Kernel Cache</key>
<string>/System/Library/Caches/com.apple.kext.caches/Startup/kernelcache</string>
<key>Kernel Flags</key>
<string>boot-uuid=7D157119-0CE8-4761-B474-0BBFFC9D9149 rd=*uuid -v</string>
</dict>
</plist>
Could somebody tell me where to find a copy of all those control-lines in the black screen at startup from the NVMeBoot disk? Somewhere in System/Library/??
I think I will soon install Mojave.
