How to extract a value from a string using regex and a shell?

Question

I am in shell and I have this string: 12 BBQ ,45 rofl, 89 lol

Using the regexp: \\d+ (?=rofl), I want 45 as a result.

Answer 1

you can use the shell(bash for example)

$ string="12 BBQ ,45 rofl, 89 lol"
$ echo ${string% rofl*}
12 BBQ ,45
$ string=${string% rofl*}
$ echo ${string##*,}
45