SHELL :Extract a string betwen two characters in different states

Question

I have a simple variable string which comes in two possibles forms :

1. First case : tag=v1.0.2-15 , or tag=v2.0.2-15 ....

2. second case : tag=v1.0.2 , or tag=v1.1.2 .....

I need to extract always the numeric part which is just after "v" and before "-" (for the first case ) and with the last numeric char (for the second case )

to obtain finally this form of output : 1.0.2 or 1.0.2 ...

I have already used this command to get it with the first case :

grep -oP "(?<=v).+(?=-)"

but i still not able to patch it for the second problem , by the way i need a command which deals with both cases in the same time any suggestions ??

Answer 1

You could just use :

(?<=v)[0-9\.]+

Here's an example.

Answer 2

grep -oP '(?<=v)[0-9]+(\.[0-9]+)*'

This looks for a v (not part of the match) followed by string consisting of one or more digits followed by one or more strings consisting of a dot followed by one or more digits.