How to add lines to multiple following lines conditionally with awk

Question

I'm trying to add bullet points to the start of sub-bullet points.

For example, converting this text file:

*foo
  abc
  def
  ghi
*bar
  jkl mno
*hello world
  pqr stu
  vwxyz

Into this text file:

foo, abc
foo, def
foo, ghi
bar, jkl mno
hello world, pqr stu
hello world, vwxyz

This seems easy, and while I have had some ideas, I haven't been able to figure it out.

Answer 1

With awk script:

awk '/^\*/{ pfx=substr($0, 2); next }{ print pfx","$0 }' file

The output:

foo,  abc
foo,  def
foo,  ghi
bar,  jkl mno
hello world,  pqr stu
hello world,  vwxyz