I have created the following mapping in my vimrc file:
noremap <C-p> ! firefox -new-tab http://php.net/<cword><C-m>
The problem is that it proceeds to delete the line under the cursor.
How would I make this mapping work correctly?
If I understood what you're trying to do the following should work:
nmap <c-p> :!firefox -new-tab http://php.net/<c-r>=expand('<cword>')<CR><CR>
See docs for further information.
You are using noremap which means that it triggers:
You should use nnoremap or xnoremap instead. Also, note that ! is a shortcut for :.! in normal mode (acts on current line) and for :'<,'>! in visual mode (acts on current visually-selected lines). If you don't want that:
nnoremap <c-p> :!firefox ...
xnoremap <c-p> :<c-u>!firefox ...
Kfor this and only for buffers withfiletypeset tophp.