Run command in the background in vim

silent_background_process.vim

" I ended up using this for starting the long-running qdocs server in qdocs-vim (https://github.com/johansenja/qdocs-vim).
" Obviously this requires ruby to spawn the process, but that is ok here given that qdocs is written in ruby anyway

" spawn the process and grab the pid to be able to refer to later
" --disable=all just speeds up the ruby start time
let l:long_running_pid = system("ruby --disable=all -e 'print(spawn(%{long_running_shell_command}))'")

" stop the server using the pid from earlier
exe "! kill -9 " . l:long_running_pid