func ReportError(cmd *flag.FlagSet, str string, withHelp bool) {
if withHelp {
if os.Args[0] == cmd.Name() {
str += ". See '" + os.Args[0] + " --help'"
} else {
str += ". See '" + os.Args[0] + " " + cmd.Name() + " --help'"
}
}
fmt.Fprintf(cmd.Out(), "docker: %s.\n", str)
os.Exit(1)
}