vim regex find and replace

Question

I want to use a regex to replace some strings in my file. I search for: %s/^ [a-z]*/ / what I want to do is to replace every [a-z]* that have 2 whitespaces with the sane [a-z] prepended with 4 whitespaces. Is there any "inplace" replacement or how would I reach that with vim?

With best regards

Answer 1

:%s/  \([a-z]*\)/    \1/g

should do the job; beware of running this multiple times, though because the result of the replace will match the input pattern :)

Answer 2

I find it more straightforward to use the \ze object to define the end of the match:

:%s/  \ze[a-z]*/    /g

so the [a-z]* is not included in the replace, but just used to match the relevant spaces.