Users and Permissions.

In modern full featured Linux distributions, users are managed by the system. And on our HPC cluster, your user is managed by your wustl key. For simply using the cluster, you may not need this section. However, it is still worth learning about users if for no other reason then there is a big overlap between how users operate and how permissions operate, and a strangely high percentage of server problems do often come down to permissions issues. Also, say you write a script or a program, and you need it to be able to execute, but it won't work just by calling it's name on the shell. What do you do. Well fix the permissions.

Whoami
Root
Sudo
chmod / chown
useradd / usermod
passwd
Groups