shell - What do S, W, D stand for in regex?

Question

In shell scripting we have for tab , s for whitespace , w for word. What are W (capital W) and D (capital D) used for ?

Answer 1

W is the opposite of w and D is the opposite of d.

It's just like S is the opposite of s.

W and D respectively will match what w and d respectively don't match.

You can have a look at this site for some more explanation.

w typically matches [A-Za-z0-9_] (ignoring the foreign characters)

W thus matches [^A-Za-z0-9_]

And since

d typically matches [0-9] (ignoring the foreign digits)

D thus matches [^0-9]