there are times you may need to reset the root password which is unknown to you.

This procedure will work fast on systems that have SELinux enabled and large volumes with lots of files which you definitely do not want to relabel as it is timeconsuming meaning long down time.

so, get on to the console, reboot the server and interupt the bootproces by pressing the up arrow button, and you get a list of boot profiles not unlike:

CentOS Linux (3.10.0-327.10.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-327.3.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-229.20.1.el7.x86_64) 7 (Core)
CentOS Linux (3.10.0-229.14.1.el7.x86_64) 7 (Core)
CentOS Linux, with Linux 0-rescue-7b58aaa412256786e56d7f23a19c4d5

from the list of boot profiles chose the last and pres e to edit the boot profile.

find the line that starts with linux16 /vmlinuz-3.10……