sed extracting group of digits

Question

I have tried to extract a number as given below but nothing is printed on screen:

echo \"This is an example: 65 apples\" | sed -n  \'s/.*\\([0-9]*\\) apples/\\1/         


        

Answer 1

What you are seeing is the greedy behavior of regex. In your first example, .* gobbles up all the digits. Something like this does it:

echo "This is an example: 65144 apples" | sed -n  's/[^0-9]*\([0-9]\+\) apples/\1/p'
65144

This way, you can't match any digits in the first bit. Some regex dialects have a way to ask for non-greedy matching, but I don't believe sed has one.