I am relatively new to Vim. Whenever I start Vim using vim LearnRuby.rb, a dollar sign appears at every line.
Why?
Open ~/.vimrc and check its contents
If you see a line like this:
set list
It means, it will display $ in every line to mark the end of line.
Either remove it or use :set nolist command in the vi editor.
:set nolist
will turn off special characters for the current buffer, such as tabs being presented as ^I and end of line characters showing up as $.
However, if it's doing that consistently when you run vim, you need to look into your .vimrc (or other startup file where applicable) and find out what's doing the set list that causes it.