How to Boot into Rescue Mode Or Emergency Mode In Ubuntu 20.04 / 18.04

It’s not uncommon for users to forget their login passwords or have their system suffer a corrupt filesystem. When that happens, the recommended solution is to boot into rescue or emergency mode and apply the required fixes.

The rescue mode is also referred to as the single-user mode. As the name suggests, the rescue mode is used when you want to salvage your system from a system failure, for example, boot failure or reset a password. In rescue mode, all the local filesystems are mounted. However, only salient services are started. Normal services such as network services will not be started.