Lab 3

lantech19446

So in the lesson there's very little mention of installing Grub they mention configuring grub and basically everything they tell you is followed by but you should never ever do this by hand. Grub2 is accompanied by one command to install it sudo grub2-install /dev/sda followed by this note of yep there's a lot of flags that need to be set in addition to this and messing it up will mess up your whole system, Grub1 is simpler but still requires a litany of editing. I didn't pay much attention with the install instructions because there were so many things saying don't do this that it seemed like it was just being covered out of prudence so I guess my questions are as follows.

1. Do I actually need to know how to perform this for the exam

2. How on earth can I practice doing this???

coop

I don't understand what your problem is.

The text says in section 3.3 that you must be careful before you run grub2-install as specifying the wrong options can brick your system. This is equivalent to saying look before you cross the street. Let's ignore Grub1 because it is obsolete (and you can't even take the exam on CentOS6 anymore which uses grub1).

As far as configuring by hand the lesson does indeed tell you to configure the files in /etc by hand; it says do not configure the files in /boot/grub or /boot/grub2 by hand.
This is section 3.5.

I don't know what is on the exam, but common sense says that if you are taking it on a virtual machine in the cloud, messing with grub is very unlikely because if you make a mistake, a bad one, your test is over.

You practice messing with Grub by either
1) Working with virtual machines. Note if you make it unbootable, you can usually mount the hard disk in the VM from within the host, any hypervisor has such capability, and you can restore a backup configuration file. This is the best method.
2) Working with dual (or multiple) boot machine, so you have another operating system to boot into and fix things.

As a matter of principle, I never give people detailed instructions for how to mess with their grub setup, partitioning, resizing and moving filesystems and partitions etc, unless I am in the room to deal with the consequences. It's not really that difficult, but a little bit of knowledge can be a dangerous thing and make things hard to fix for the non-expert.

Furthermore, every distribution (and version of distros) tends to customize the grub setup and it is impossible to give a complete description that doesn't go stale and become misleading. Thus, like in many other matters, keep your eyes open, read man pages and look at files, and don't expect it to be something that can be done without understanding. That's one reason we do not go into very deep detail on a subject like this.