How can they certificate you in something you don't even know what is about
Anyway, I'll learn more about Red Hat, Fedora, Ubuntu, Shell Scripting, and
the way a GNU/Linux system works.
What type of users can it have, what type of permissions
what is /bin/ /dev/ /boot/ /etc/ (I do mean etc)
what is ext4 F2fs btrfs ext3 ext2 and file systems in general
What is ssh and how to use it
What is scp and how to use it
What is a kernel
What is a shell and which types exist
What is a bootloader (grub, syslinux)
What is an init (openrc, sysv)
What is systemd
What is apparmor, SELinux, grsecurity
Maybe learn a little bit about telnet.
How the kernel works, how it treats memory, what is a system call, what is a
process, (I don't know much, but you get the idea)
Also things related to LAMP servers.
You probably already know all this, but I am trying to be explicit as maybe
there is something you don't and it will help you.
In general the arch wiki is great