private void showProperty(final String propertyName) throws UnrecognizedCommandException {
		java.util.Set<String> properties = Set.properties;
		Properties systemProp = Conf.getSystemProperties();
		StringBuilder sb = new StringBuilder();
		if (null == propertyName) {
			int len1 = 0;
			for (String name : properties) {
				if (name.length() > len1) len1 = name.length();
			}
			len1 += 2;
			int c = 0;
			for (String name : Set.properties) {
				sb.append(name).append(TextUtilities.repeatStringPattern(" ", len1 - name.length())).append(systemProp.get(name));
				if (++c < Set.properties.size()) sb.append(LINE_SEPARATOR);
			}
		} else {
			if (!properties.contains(propertyName)) throw new UnrecognizedCommandException(COMMAND_NAME + ", property [" + propertyName + "] not found");
			sb.append(propertyName).append("  ").append(systemProp.get(propertyName));
		}
		out.println(sb.toString());
	}