How to Boot Oracle Linux 7 (OL7) Into Rescue And Emergency Modes Via 'systemd'
In OL7, both rescue mode and emergency mode are systemd targets (that replace runlevels of previous OL versions).
Rescue mode allows the system to be repaired in situations when it is unable to complete its regular boot process.
Emergency mode provides a minimal environment allowing the system to be repaired even in situations when the system is unable to enter rescue mode.
Booting into Emergency mode (target)
1) During boot, when the GRUB2 menu is displayed, press the e key i.e. edit.
2( Append the following parameter to the linux16 line on a x86-64 system, or to the