@b0rkJulia Evans nit: I'm not sure 'nohup' is a builtin? All of bash, zsh and fish report "nohup is /usr/bin/nohup" in response to "type nohup". But perhaps it is in some other shell? That would be easy to believe.
Even more persnickety and perhaps too much detail: 'kill' is a builtin _as well_ as being an external command, because the builtin version can understand job-control specifications like %1 as well as plain pids.