问题
Here is a map command.
nnoremap <F5> :w\|!R %<CR>
1.what is the meaning of \ here?
2. does | mean pipe ?
回答1:
The | character separates two Ex commands, see :help :|. It's like ; in programming languages like C and Java. It has nothing to do with pipes; Vim hasn't that concept (which is typically found in shells).
It is escaped here so that the entire command sequence belongs to the mapping; i.e. it maps to :w|!R %<CR>. Without escaping, Vim would execute the following instead:
:nnoremap <F5> :w
:!R %<CR>
Note that you can also write <Bar> (cp. :help key-notation) instead of \|, and the former is more frequently used.
来源：https://stackoverflow.com/questions/21185216/what-is-the-meaning-of-in-a-map-vim-command