### Question:
OSUtils { public static String exeCmd(String command) throws IOException { StringTokenizer st = new StringTokenizer(command); String[] cmdArray = new String[st.countTokens()]; for (int i = 0; st.hasMoreTokens(); i++) { cmdArray[i] = st.nextToken(); } return exeShell(cmdArray); } private  OSUtils(); static double memoryUsage(); static double availablePhysicalMemorySize(); static double totalMemorySize(); static double loadAverage(); static double cpuUsage(); static List<String> getUserList(); static boolean createUser(String userName); static String getGroup(); static String exeCmd(String command); static String exeShell(String[] command); static int getProcessID(); static boolean isMacOS(); static boolean isWindows(); static String getOSName(); static Boolean checkResource(double systemCpuLoad, double systemReservedMemory); static Boolean checkResource(Configuration conf, Boolean isMaster); static final ThreadLocal<Logger> taskLoggerThreadLocal; static final String TWO_DECIMAL; static final double NEGATIVE_ONE; }### Answer:
@Test public void exeCmd() { if(OSUtils.isMacOS() || !OSUtils.isWindows()){ try { String result = OSUtils.exeCmd("echo helloWorld"); Assert.assertEquals("helloWorld\n",result); } catch (IOException e) { Assert.fail("exeCmd " + e.getMessage()); } } }