Even though it is great advice, there is some sadness in the fact that it should even be advice. Apart from knowing how to enter code, the other most basic thing should be knowing how to lookup code?
Nitpick: it shouldn't be a CLI tool, a proper text editor or even IDE allows you to perform the same thing as well. Many text editors also have a pretty good indexing which will show matches on hovering the mouse. Never good enough to blindly trust, but usually faster and does a good job as 'quick win' for the first attempt.