How to use grep to match lines where the first character falls in a range?

Question

I am trying to grep lines where the first character is an A, B, or C.

I am trying this:

grep -i "^[a-c]*" data.txt

I want it to only care about the very first character, the rest of the line I don't care about.

Answer 1

Because you have used the * (zero or more) quantifier, your expression is going to match every line. Change it to

grep -i "^[a-c]" data.txt

and it should work as you intend.