I sat all day, tried to understand prasadbabu's code, then i asked for help to id-perl.

Then someone named Jacinta Richardson told me about this, and she said :

/
      aaaaa               # Find me aaaaa
           (?:            # Followed by, but do not capture
            (?:           # Group but do not capture
                (?!       # Something which is not
                    aaaaa
                    .    #and any char including newline
                )
            )*             # As many as possible
        )
    /gs        # Repeat the match, dots can include newlines
[download]

The first grouping is unnessary, but not a problem.

Negative look-aheads ask the regular _expression to look at the nextvalue and only include it in the match if it does not match that part of the _expression.

Thus the regular _expression finds: aaaaa\nbbbbb\nccccc\n

in its first run, stopping at the "aaaaa\n" which matches the negative look-ahead and then in its second run finds: aaaaa\nddddd\neeeee\n

That's what she said, and then i realize that Jacinta Richadson known as jarich here.

Thanks for your time Jarich, and hope this help jeanluca too