Linux / Unix interview questions

Here are some Linux / Unix questions you might encounter during a technical interview.

Describe Unix run levels. What does run-level 3 mean?

A program is running slow. What do you do?

You want to schedule a process to run every Tuesday at 1:00 am. What do you do?

What do these shell variables mean?

* $$ - Process ID of self
* $! - Process ID of last background process
* $_ - Last argument

When I define an environment variable, what does EXPORT mean?

What is a journaling file system and why would I want to use one?