public static boolean isValidLinuxUserName(String str) {
        return LINUX_USERNAME_PATTERN.matcher(str).matches();
    }
@Test
    public void testIsValidLinuxUserName() {
        String name1 = "10000";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name1));

        String name2 = "00hayden";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name2));

        String name3 = "hayde123456789123456789123456789";
        Assertions.assertFalse(RegexUtils.isValidLinuxUserName(name3));

        String name4 = "hayd123456789123456789123456789";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name4));

        String name5 = "h";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name5));

        String name6 = "hayden";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name6));

        String name7 = "00hayden_0";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name2));

        String name8 = "00hayden.8";
        Assertions.assertTrue(RegexUtils.isValidLinuxUserName(name2));
    }