There is a huge array of linux courses that you can pick and choose from, but the RHCE certification is one of the top ones in the world. You would possess the required operational skills, knowledge and understanding of the operating system for one of the most commonly used server operating systems all over the world.

If you want to be able to work for any company, then this is the certification that you should be aiming for. Start at the beginning of the classes to ensure that you are picking up every trick and detail that you can learn.