Find out how your Linux system was booted (with what command)

If you would like to know how your linux system was booted type the following to give you the information that you need:

$ cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-3.13.0-62-generic.efi.signed root=UUID=7ef51656-acfc-4d01-aa94-90f7042b2e28 ro quiet splash vt.handoff=7