Linux command line quiz

Ten questions across the whole chapter. Each answer explains why, so a wrong guess still teaches you something. Aim for eight before moving on to chapter 3.

Which program reads the commands you type and runs them?
How does a Linux distribution differ from the Linux kernel?
Your prompt ends with
In head -n 20 /var/log/secure, what is -n 20?
SSH refuses to connect to servera and reports that its host key has changed. What is the right first step?
Which command shows a long log one screen at a time and lets you search it?
What does wc -l /etc/passwd /etc/group print?
You typed a long command and want to run it again with one word changed. What is the quickest way?
What is the difference between !! and the up arrow?
Why does a command you ran three times in a row appear only once in history on RHEL?