System Enumeration

Get kernel version

uname -a

cat /proc/version
cat /etc/issue

It can be useful to know the hostname in CTF situations as it can relate to the required exploit to escalate privileges

View the architecture

lscpu

Some exploits may require multiple threads or cores, if the machine doesn't have the required amount then the exploit won't work

View processes

ps aux
ps aux | grep root

They will be in the order that they were issued