- {string}
The subprocess.spawnfile property indicates the executable file name of
the child process that is launched.
For [child_process.fork()][], its value will be equal to
[process.execPath][].
For [child_process.spawn()][], its value will be the name of
the executable file.
For [child_process.exec()][], its value will be the name of the shell
in which the child process is launched.
