We have linked to relevant training courses from other institutions.
Rather than recreate them we recommend that you access them directly.
Here is a partial list from each site:
Cornell Virtual Workshops
We run RHEL/CentOS 6 Linux on our high-performance systems.
If you have never used Linux before or have had very limited use, read this useful guide:
If you have learned Linux in the past but want a quick reference to the syntax of commands, then read this: