### Question:
Shell { public static String execCommand(String ... cmd) throws IOException { return execCommand(cmd, -1); } Shell(long timeout); int exitCode(); Process process(); static String execCommand(String ... cmd); static String execCommand(String[] cmd, long timeout);  }### Answer:
@Test public void testEchoHello() throws Exception { assumeTrue(!OperatingSystem.IS_WINDOWS); String output = Shell.execCommand("echo", "hello"); assertEquals("hello\n", output); }
@Test public void testHeadDevZero() throws Exception { assumeTrue(!OperatingSystem.IS_WINDOWS); final int length = 100000; String output = Shell.execCommand("head", "-c", Integer.toString(length), "/dev/zero"); assertEquals(length, output.length()); }