This is the silent installation for the silnite9 installer found at https://eclecticlight.co/downloads/
curl "https://eclecticlightdotcom.files.wordpress.com/2022/10/silnite9.zip" -o /tmp/silnite9.zip
cd /tmp
unzip /tmp/silnite9.zip
installer -pkg /tmp/silnite9/silniteInstaller.pkg -target /
run the binary to get information on the current state of updates:
/usr/local/bin/silnite am
Here is the zip file just in case the original is not available anymore: Download
Just in case you wonder:
Here is the explanation on “Why is my Mac’s Gatekeeper data so out of date?”