I'm still using Unity on Ubuntu 18.04. It froze solid while I was working. I used
alt+f2 to switch to a terminal and ran
unity --replace in an attempt to get my desktop back without losing my work. However, it just killed the desktop, including all my programs, and kicked me out to the login screen. I can reproduce this reliably; running
unity --replace in either the tty or in gnome-terminal results in the desktop session getting completely killed, and I need to start a new login.
unity --replace no longer supported? Is there some replacement? This trick has saved me many times in the past decade; I'd be very sad if this is permanently gone from Ubuntu.