Boot Process
Some useful links to explain the concepts of the Boot Process
Concepts
Overview of the Linux Boot process
https://0xax.gitbooks.io/linux-insides/content/Booting/linux-bootstrap-1.html
http://www.slashroot.in/linux-booting-process-step-step-tutorial-understanding-linux-boot-sequence
http://www.golinuxhub.com/2014/03/step-by-step-linux-boot-process.html?
http://linoxide.com/booting/boot-process-of-linux-in-detail/
http://bencane.com/2013/09/16/understanding-a-little-more-about-etcprofile-and-etcbashrc/
Difference between commands for bringing down a linux server
Difference between GRUB / LILO
Is a separate boot partition necessary in Linux OS?
Commands
Configuration
http://www.if-not-true-then-false.com/2012/delete-remove-old-kernels-on-fedora-centos-red-hat-rhel/
https://linuxconfig.org/how-to-remove-unused-kernel-images-from-centos-linux-system
https://markmcb.com/2013/02/04/cleanup-unused-linux-kernels-in-ubuntu/
http://www.ostechnix.com/how-to-create-bootable-usb-drive-using-dd-command/