int Tool::main( int argc , char ** argv ) {
        static StaticObserver staticObserver;

        cmdLine.prealloc = false;

        // The default value may vary depending on compile options, but for tools
        // we want durability to be disabled.
        cmdLine.dur = false;

        _name = argv[0];

        /* using the same style as db.cpp */
        int command_line_style = (((po::command_line_style::unix_style ^
                                    po::command_line_style::allow_guessing) |
                                   po::command_line_style::allow_long_disguise) ^
                                  po::command_line_style::allow_sticky);
        try {
            po::options_description all_options("all options");
            all_options.add(*_options).add(*_hidden_options);

            po::store( po::command_line_parser( argc , argv ).
                       options(all_options).
                       positional( _positonalOptions ).
                       style(command_line_style).run() , _params );

            po::notify( _params );
        }
        catch (po::error &e) {
            cerr << "ERROR: " << e.what() << endl << endl;
            printHelp(cerr);
            ::_exit(EXIT_BADOPTIONS);
        }

        // hide password from ps output
        for (int i=0; i < (argc-1); ++i) {
            if (!strcmp(argv[i], "-p") || !strcmp(argv[i], "--password")) {
                char* arg = argv[i+1];
                while (*arg) {
                    *arg++ = 'x';
                }
            }
        }

        if ( _params.count( "help" ) ) {
            printHelp(cout);
            ::_exit(0);
        }

        if ( _params.count( "version" ) ) {
            printVersion(cout);
            ::_exit(0);
        }

        if ( _params.count( "verbose" ) ) {
            logLevel = 1;
        }

        for (string s = "vv"; s.length() <= 10; s.append("v")) {
            if (_params.count(s)) {
                logLevel = s.length();
            }
        }


#ifdef MONGO_SSL
        if (_params.count("ssl")) {
            mongo::cmdLine.sslOnNormalPorts = true;
        }
#endif

        preSetup();

        bool useDirectClient = hasParam( "dbpath" );

        if ( ! useDirectClient ) {
            _host = "127.0.0.1";
            if ( _params.count( "host" ) )
                _host = _params["host"].as<string>();

            if ( _params.count( "port" ) )
                _host += ':' + _params["port"].as<string>();

            if ( _noconnection ) {
                // do nothing
            }
            else {
                string errmsg;

                ConnectionString cs = ConnectionString::parse( _host , errmsg );
                if ( ! cs.isValid() ) {
                    cerr << "invalid hostname [" << _host << "] " << errmsg << endl;
                    ::_exit(-1);
                }

                _conn = cs.connect( errmsg );
                if ( ! _conn ) {
                    cerr << "couldn't connect to [" << _host << "] " << errmsg << endl;
                    ::_exit(-1);
                }

                (_usesstdout ? cout : cerr ) << "connected to: " << _host << endl;
            }

        }
        else {
            if ( _params.count( "directoryperdb" ) ) {
                directoryperdb = true;
            }
            verify( lastError.get( true ) );

            if (_params.count("journal")){
                cmdLine.dur = true;
            }

            Client::initThread("tools");
            _conn = new DBDirectClient();
            _host = "DIRECT";
            static string myDbpath = getParam( "dbpath" );
            dbpath = myDbpath.c_str();
            try {
                acquirePathLock();
            }
            catch ( DBException& ) {
                cerr << endl << "If you are running a mongod on the same "
                     "path you should connect to that instead of direct data "
                     "file access" << endl << endl;
                dbexit( EXIT_FS );
                ::_exit(EXIT_FAILURE);
            }

            FileAllocator::get()->start();

            dur::startup();
        }

        if ( _params.count( "db" ) )
            _db = _params["db"].as<string>();

        if ( _params.count( "collection" ) )
            _coll = _params["collection"].as<string>();

        if ( _params.count( "username" ) )
            _username = _params["username"].as<string>();

        if ( _params.count( "password" )
                && ( _password.empty() ) ) {
            _password = askPassword();
        }

        if (_params.count("ipv6"))
            enableIPv6();

        int ret = -1;
        try {
            ret = run();
        }
        catch ( DBException& e ) {
            cerr << "assertion: " << e.toString() << endl;
            ret = -1;
        }
        catch(const boost::filesystem::filesystem_error &fse) {
            /*
              https://jira.mongodb.org/browse/SERVER-2904

              Simple tools that don't access the database, such as
              bsondump, aren't throwing DBExceptions, but are throwing
              boost exceptions.

              The currently available set of error codes don't seem to match
              boost documentation.  boost::filesystem::not_found_error
              (from http://www.boost.org/doc/libs/1_31_0/libs/filesystem/doc/exception.htm)
              doesn't seem to exist in our headers.  Also, fse.code() isn't
              boost::system::errc::no_such_file_or_directory when this
              happens, as you would expect.  And, determined from
              experimentation that the command-line argument gets turned into
              "\\?" instead of "/?" !!!
             */
#if defined(_WIN32)
            if (/*(fse.code() == boost::system::errc::no_such_file_or_directory) &&*/
                (fse.path1() == "\\?"))
                printHelp(cerr);
            else
#endif // _WIN32
                cerr << "error: " << fse.what() << endl;

            ret = -1;
        }

        if ( currentClient.get() )
            currentClient.get()->shutdown();

        if ( useDirectClient )
            dbexit( EXIT_CLEAN );

        fflush(stdout);
        fflush(stderr);
        ::_exit(ret);
    }