ntool/ncmd/cmd_darwin.go

package ncmd

import (
	"os/exec"
	"syscall"
)

// terminateProcess stops the command by sending its process group a SIGTERM signal.
// Stop is idempotent. An error should only be returning to the rare case that
// Stop is called immediately after the command ends but before Start can
// update its internal state.
func terminateProcess(pid int) error {
	// Signal the process group (-pid), not just the process, so that the process
	// and all its children are signaled. Else, child processes can keep running and
	// keep the stdout/stderr fd open and cause cmd.Wait to hang.
	return syscall.Kill(-pid, syscall.SIGTERM)
}

// Set process group ID so the cmd and all its children become a new
// process group. This allows Stop to SIGTERM the cmd's process group
// without killing this process (i.e. this code here).
func setProcessGroupID(cmd *exec.Cmd) {
	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
}