Vim Regex Capture Groups [bau -> byau : ceu -> cyeu]

Question

I have a list of words:

bau
ceu
diu
fou
gau

I want to turn that list into:

byau
cyeu
dyiu
fyou
gyau

I uns

Answer 1

You also have to escape the Grouping paranthesis:

:%s/\(\w\)\(\w\w\)/\1y\2/g

That does the trick.