How to extract value betwen two string using regex?

Question

Here is the demo String:

beforeValueAfter

Assume that I know the value I want is between "before" and "After" I want to extact the "Value" using the regex....

pervious909078375639355544after

Assume that I know the value I want is between "pervious90907" and "55544after" I want to extact the "83756393" using the regex....

thx in advance.

Answer 1

Try this regular expression:

pervious90907(.*?)55544after

That will get you the shortest string (note the non-greedy *? quantifier) between pervious90907 and 55544after.

Answer 2

The answer depends on two things:

• If you know exactly what the value consists of (if you know it will be digits, etc., it makes it easier). If it could be anything, the answer is a little harder.
• If your system is greedy/ungreedy by default, it affects the way you'd set up the expression. I will assume it is greedy by default.

If it can be anything (the ? will be needed to toggle the .* to ungreedy because ".*" also matches "After":

/before(.*?)After/

If you know it is digits:

/before(\d*)After

If it could be any word characters (0-9, a-z, A-Z, _):

/before(\w*?)After

Answer 3

The regex should be like this:

previous([0-9]*)after

Answer 4

bash-3.2$ echo pervious909078375639355544after | perl -ne 'print "$1\n" if /pervious90907(.*)55544after/'
83756393