Start a background process using the PowerShell cmdlet
Start-Process-PassThru on Windows or the ampersand & on
Unix, and return the process ID.
bg_process(
  command,
  args = character(),
  verbose = getOption("xfun.bg_process.verbose", FALSE)
)The process ID as a character string.
The system command and its arguments. They do not need to
be quoted, since they will be quoted via shQuote() internally.
If FALSE, suppress the output from stdout (and also
stderr on Windows). The default value of this argument can be set via a
global option, e.g., options(xfun.bg_process.verbose = TRUE).
proc_kill() to kill a process.