Depends on how you think of it. Maybe I shouldn't have used the word "career" here, as I wrote code long before people paid me for it, and aim to keep doing it long after.
I've found this to be THE best book for learning awk and regular expressions. Its astounding how clear and structured the material is and how easy it is to retain in your head when presented that way.
https://irreal.org/blog/?p=10746