I have a file which looks somewhat like this

fsdfsdfsdfsdfsf sdfsdf fffhgf $$
fgsdfdsdfsf dfsdfsdfdsfd $
xvfsfsffsd $
fsdfsdfsd $
cvbvcbvcvbcvb $
ghggf hgfhgf gfhghgf $ $
sdfdfddsdf dfsdfdsfsdfdfdfff $$

Now I want to append all the lines ending with '$' to the very first line it meets ending wth $ traversing back .

Eg here the o/p should look like this

fsdfsdfsdfsdfsf sdfsdf fffhgf $$
fgsdfdsdfsf dfsdfsdfdsfd xvfsfsffsd fsdfsdfsd cvbvcbvcvbcvb $$
ghggf hgfhgf gfhghgf $ $
sdfdfddsdf dfsdfdsfsdfdfdfff $$

Can anyone help....