private void usage(String str) {
		switch (COMMAND.getCommand(str)) {
		case A:
			System.out.println("Usage: -a \"filename\"");
			break;
		case C:
			System.out.println("Usage: -c <number>");
			break;
		case F:
			System.out.println("Usage: -f \"filename\"");
			break;
		case H:
			System.out.println("Usage: -h <hostname:port>");
			break;
		case U:
			System.out.println("Usage: -u <certificate>");
			break;
		case V:
			System.out.println("Usage: -v \"filename\" \"certificate\"");
			break;
		default:
			// List all commands available
			System.out.println("-a <filename>" + "\t\t\t add or replace a file to the trustcloud");
			System.out.println("-c <number>" + "\t\t\t provide the required circumference (length) of a ring of trust");
			System.out.println("-f <filename>" + "\t\t\t fetch an existing file from the trustcloud server (simply sent to stdout)");
			System.out.println("-h <hostname:port>" + "\t\t provide the remote address hosting the trustcloud server");
			System.out.println("-l	" + "\t\t\t list all stored files and how they are protected");
			System.out.println("-q	" + "\t\t\t quit the program and exit now");
			System.out.println("-u <certificate>" + "\t\t upload a certificate to the trustcloud server");
			System.out.println("-v <filename> <certificate>" + "\t vouch for the authenticity of an existing file in the trustcloud server using the indicated certificate");
			System.out.println("exit	" + "\t\t\t quit the program and exit now");
			break;
		}
	}