Grep is a must learn command for working with linux or for scripting.
I found that for learning basic material, watching a video is more engaging and helped with retention. For more complex concepts and posts with a lot of technical detail I still prefer the written page.
There are many great grep tutorials on youtube. I have concentrated on making the tutorial easy to follow for newbies.
Hopefully the knowledge presented here will help you with the grep command to search log files and configuration files with some confidence.
I will put up another tutorial with more advance examples in the next post.