diff --git a/grive/src/main.cc b/grive/src/main.cc
index 9516a2c..cf3a3d1 100644
--- a/grive/src/main.cc
+++ b/grive/src/main.cc
@@ -46,9 +46,6 @@
 
 const std::string client_id		= "22314510474.apps.googleusercontent.com" ;
 const std::string client_secret	= "bl4ufi89h-9MkFlypcI7R785" ;
-const std::string defaultRootFolder = ".";
-const std::string defaultConfigFileName = ".grive";
-const char *configFileEnvironmentVariable = "GR_CONFIG";
 
 using namespace gr ;
 namespace po = boost::program_options;
@@ -105,8 +102,6 @@ int Main( int argc, char **argv )
 {
 	InitGCrypt() ;
 	
-	std::string rootFolder = defaultRootFolder;
-	
 	// construct the program options
 	po::options_description desc( "Grive options" );
 	desc.add_options()
@@ -129,6 +124,7 @@ int Main( int argc, char **argv )
 	po::store(po::parse_command_line( argc, argv, desc), vm );
 	po::notify(vm);
 	
+	// simple commands that doesn't require log or config
 	if ( vm.count("help") )
 	{
 		std::cout << desc << std::endl ;
@@ -144,31 +140,9 @@ int Main( int argc, char **argv )
 	// initialize logging
 	InitLog(vm) ;
 	
-	boost::shared_ptr<Config> config ;
+	Config config(vm) ;
 	
-	// config file will be (in order of preference)
-	// value specified in environment string
-	// value specified in defaultConfigFileName in path from commandline --path
-	// value specified in defaultConfigFileName in current directory
-	const char *envConfigFileName = ::getenv( configFileEnvironmentVariable ) ;
-	if (envConfigFileName) {
-		config.reset(new Config(envConfigFileName));
-
-	} else if ( vm.count( "path" ) ) {
-		rootFolder = vm["path"].as<std::string>();
-		config.reset(new Config( fs::path(rootFolder) / fs::path(defaultConfigFileName) ));
-
-	} else {
-		config.reset(new Config( defaultConfigFileName) );
-	}
-	
-	// misc options
-	Json options ;
-	options.Add( "log-xml", Json(vm.count("log-xml") > 0) ) ;
-	options.Add( "new-rev", Json(vm.count("new-rev") > 0) ) ;
-	options.Add( "force",	Json(vm.count("force") > 0 ) ) ;
-	
-	Log( "config file name %1%", config->ConfigFile().string(), log::verbose );
+	Log( "config file name %1%", config.Filename(), log::verbose );
 
 	if ( vm.count( "auth" ) )
 	{
@@ -188,14 +162,14 @@ int Main( int argc, char **argv )
 		token.Auth( code ) ;
 		
 		// save to config
-		config->Get().Add( "refresh_token", Json( token.RefreshToken() ) ) ;
-		config->Save() ;
+		config.Set( "refresh_token", Json( token.RefreshToken() ) ) ;
+		config.Save() ;
 	}
 	
 	std::string refresh_token ;
 	try
 	{
-		refresh_token = config->Get()["refresh_token"].Str() ;
+		refresh_token = config.Get("refresh_token").Str() ;
 	}
 	catch ( Exception& e )
 	{
@@ -210,7 +184,7 @@ int Main( int argc, char **argv )
 	OAuth2 token( refresh_token, client_id, client_secret ) ;
 	AuthAgent agent( token, std::auto_ptr<http::Agent>( new http::CurlAgent ) ) ;
 
-	Drive drive( &agent, options, rootFolder ) ;
+	Drive drive( &agent, config.GetAll() ) ;
 	drive.DetectChanges() ;
 
 	if ( vm.count( "dry-run" ) == 0 )
@@ -221,7 +195,7 @@ int Main( int argc, char **argv )
 	else
 		drive.DryRun() ;
 	
-	config->Save() ;
+	config.Save() ;
 	Log( "Finished!", log::info ) ;
 	return 0 ;
 }
diff --git a/libgrive/src/drive/Drive.cc b/libgrive/src/drive/Drive.cc
index 028e62c..82cfc74 100644
--- a/libgrive/src/drive/Drive.cc
+++ b/libgrive/src/drive/Drive.cc
@@ -51,10 +51,10 @@ namespace
 	const std::string state_file = ".grive_state" ;
 }
 
-Drive::Drive( http::Agent *http, const Json& options, const std::string &rootFolder) :
-	m_http( http ),
-	m_state( fs::path(rootFolder), fs::path(rootFolder) / fs::path(state_file), options ),
-	m_rootFolder(rootFolder),
+Drive::Drive( http::Agent *http, const Json& options ) :
+	m_http		( http ),
+	m_root		( options["path"].Str() ),
+	m_state		( m_root / state_file, options ),
 	m_options	( options )
 {
 	assert( m_http != 0 ) ;
@@ -128,7 +128,7 @@ void Drive::SyncFolders( )
 void Drive::DetectChanges()
 {
 	Log( "Reading local directories", log::info ) ;
-	m_state.FromLocal( m_rootFolder ) ;
+	m_state.FromLocal( m_root ) ;
 	
 	long prev_stamp = m_state.ChangeStamp() ;
 	Trace( "previous change stamp is %1%", prev_stamp ) ;
diff --git a/libgrive/src/drive/Drive.hh b/libgrive/src/drive/Drive.hh
index bcae37c..5424f44 100644
--- a/libgrive/src/drive/Drive.hh
+++ b/libgrive/src/drive/Drive.hh
@@ -40,7 +40,7 @@ class Entry ;
 class Drive
 {
 public :
-	Drive( http::Agent *http, const Json& options, const std::string &rootFolder ) ;
+	Drive( http::Agent *http, const Json& options ) ;
 
 	void DetectChanges() ;
 	void Update() ;
@@ -59,8 +59,8 @@ private :
 private :
 	http::Agent 	*m_http ;
 	std::string		m_resume_link ;
+	fs::path		m_root ;
 	State			m_state ;
-  fs::path		m_rootFolder;
 	Json			m_options ;
 } ;
 
diff --git a/libgrive/src/drive/Resource.cc b/libgrive/src/drive/Resource.cc
index 53e4fc4..e64bd0f 100644
--- a/libgrive/src/drive/Resource.cc
+++ b/libgrive/src/drive/Resource.cc
@@ -58,8 +58,8 @@ const std::string xml_meta =
 
 
 /// default constructor creates the root folder
-Resource::Resource(const fs::path& rootFolder) :
-	m_name		( rootFolder.string() ),
+Resource::Resource(const fs::path& root_folder) :
+	m_name		( root_folder.string() ),
 	m_kind		( "folder" ),
 	m_id		( "folder:root" ),
 	m_href		( root_href ),
diff --git a/libgrive/src/drive/Resource.hh b/libgrive/src/drive/Resource.hh
index 9406c6f..5d4f034 100644
--- a/libgrive/src/drive/Resource.hh
+++ b/libgrive/src/drive/Resource.hh
@@ -51,7 +51,7 @@ public :
 	typedef Children::const_iterator iterator ;
 	
 public :
-	Resource(const fs::path& rootFolder) ;
+	Resource(const fs::path& root_folder) ;
 	Resource( const std::string& name, const std::string& kind ) ;
 	
 	// default copy ctor & op= are fine
diff --git a/libgrive/src/drive/State.cc b/libgrive/src/drive/State.cc
index cd2aec6..43e6367 100644
--- a/libgrive/src/drive/State.cc
+++ b/libgrive/src/drive/State.cc
@@ -32,9 +32,9 @@
 
 namespace gr {
 
-State::State( const fs::path& rootFolder, const fs::path& filename, const Json& options  ) :
-    m_res(rootFolder),
-	m_cstamp( -1 )
+State::State( const fs::path& filename, const Json& options  ) :
+    m_res		( options["path"].Str() ),
+	m_cstamp	( -1 )
 {
 	Read( filename ) ;
 	
diff --git a/libgrive/src/drive/State.hh b/libgrive/src/drive/State.hh
index 2cc2405..a0e1213 100644
--- a/libgrive/src/drive/State.hh
+++ b/libgrive/src/drive/State.hh
@@ -43,7 +43,7 @@ public :
 	typedef ResourceTree::iterator iterator ;
 
 public :
-	explicit State( const fs::path& rootFolder, const fs::path& filename, const Json& options ) ;
+	explicit State( const fs::path& filename, const Json& options ) ;
 	~State() ;
 	
 	void FromLocal( const fs::path& p ) ;
diff --git a/libgrive/src/util/Config.cc b/libgrive/src/util/Config.cc
index 62a8333..1a19eff 100644
--- a/libgrive/src/util/Config.cc
+++ b/libgrive/src/util/Config.cc
@@ -26,39 +26,80 @@
 #include <iostream>
 #include <iterator>
 
+namespace po = boost::program_options;
+
 namespace gr {
 
-Config::Config(const fs::path& configFile) :
-	m_configFile(configFile),
-	m_cfg( Read() )
+const std::string	default_filename	= ".grive";
+const char			*env_name			= "GR_CONFIG";
+const std::string	default_root_folder = ".";
+
+Config::Config( const fs::path& root_path ) :
+	m_path( GetPath( root_path ) )
 {
-	if (configFile.empty())
-	{
-		throw Error() << expt::ErrMsg("Config cannot be initalised with an empty string.");
-	}
+	m_file = Read() ;
 }
 
-const fs::path& Config::ConfigFile() const
+Config::Config( const po::variables_map& vm )
 {
-	return m_configFile ;
+	m_cmd.Add( "log-xml",	Json(vm.count("log-xml") > 0) ) ;
+	m_cmd.Add( "new-rev",	Json(vm.count("new-rev") > 0) ) ;
+	m_cmd.Add( "force",		Json(vm.count("force") > 0 ) ) ;
+	m_cmd.Add( "path",		Json(vm.count("path") > 0
+		? vm["path"].as<std::string>()
+		: default_root_folder ) ) ;
+	
+	m_path	= GetPath( fs::path(m_cmd["path"].Str()) ) ;
+	m_file	= Read( ) ;
+}
+
+fs::path Config::GetPath( const fs::path& root_path )
+{
+	// config file will be (in order of preference)
+	// value specified in environment string
+	// value specified in defaultConfigFileName in path from commandline --path
+	// value specified in defaultConfigFileName in current directory
+	const char *env = ::getenv( env_name ) ;
+	return root_path / (env ? env : default_filename) ;
+}
+
+const fs::path Config::Filename() const
+{
+	return m_path ;
 }
 
 void Config::Save( )
 {
-	StdioFile file( m_configFile.string(), 0600 ) ;
-	m_cfg.Write( file ) ;
+	StdioFile file( m_path.string(), 0600 ) ;
+	m_file.Write( file ) ;
 }
 
-Json& Config::Get()
+void Config::Set( const std::string& key, const Json& value )
 {
-	return m_cfg ;
+	m_file.Add( key, value ) ;
+}
+
+Json Config::Get( const std::string& key ) const
+{
+	return m_cmd.Has(key) ? m_cmd[key] : m_file[key] ;
+}
+
+Json Config::GetAll() const
+{
+	Json::Object obj		= m_file.AsObject() ;
+	Json::Object cmd_obj	= m_cmd.AsObject() ;
+	
+	for ( Json::Object::iterator i = cmd_obj.begin() ; i != cmd_obj.end() ; ++i )
+		obj[i->first] = i->second ;
+	
+	return Json( obj ) ;
 }
 
 Json Config::Read()
 {
 	try
 	{
-		return Json::ParseFile( m_configFile.string() ) ;
+		return Json::ParseFile( m_path.string() ) ;
 	}
 	catch ( Exception& e )
 	{
diff --git a/libgrive/src/util/Config.hh b/libgrive/src/util/Config.hh
index 30ef116..8349ce3 100644
--- a/libgrive/src/util/Config.hh
+++ b/libgrive/src/util/Config.hh
@@ -23,6 +23,14 @@
 #include "FileSystem.hh"
 #include "protocol/Json.hh"
 
+namespace boost
+{
+	namespace program_options
+	{
+		class variables_map ;
+	}
+}
+
 namespace gr {
 
 class Config
@@ -31,18 +39,30 @@ public :
 	struct Error : virtual Exception {} ;
 	typedef boost::error_info<struct FileTag, std::string>	File ;
 
-	Config(const fs::path& configFile) ;
+	Config( const fs::path& root_path ) ;
+	Config( const boost::program_options::variables_map& vm ) ;
+
+	const fs::path Filename() const ;
 	
-	Json& Get() ;
+	void Set( const std::string& key, const Json& value ) ;
+	Json Get( const std::string& key ) const ;
+
+	Json GetAll() const ;
 	void Save() ;
-	const fs::path &ConfigFile() const;
 
 private :
-	Json Read() ;
+	Json Read( ) ;
+	static fs::path GetPath( const fs::path& root_path ) ;
 
 private :
-	const fs::path	m_configFile;
-	Json			m_cfg ;
+	//! config file path
+	fs::path	m_path;
+	
+	//! config values loaded from config file
+	Json		m_file ;
+	
+	//! config values from command line
+	Json		m_cmd ;
 } ;
 	
 } // end of namespace
diff --git a/libgrive/test/util/ConfigTest.cc b/libgrive/test/util/ConfigTest.cc
index 33a427d..94b3eef 100644
--- a/libgrive/test/util/ConfigTest.cc
+++ b/libgrive/test/util/ConfigTest.cc
@@ -36,22 +36,22 @@ ConfigTest::ConfigTest( )
 
 void ConfigTest::TestInitialiseWithEmptyString( )
 {
-  Config config("");
-  GRUT_ASSERT_EQUAL( "/home/.grive", config.ConfigFile().string()) ;
+	Config config("");
+	GRUT_ASSERT_EQUAL( "/home/.grive", config.Filename().string()) ;
 }
 
 void ConfigTest::TestInitialiseWithString( )
 {
-  Config config("/home/.grive");
-  GRUT_ASSERT_EQUAL( "/home/.grive", config.ConfigFile().string()) ;
+	Config config("/home/.grive");
+	GRUT_ASSERT_EQUAL( "/home/.grive", config.Filename().string()) ;
 }
 
 void ConfigTest::TestInitialiseWithFileSystemPath( )
 {
-  fs::path path("/home");
-  fs::path file(".grive");
-  Config config(path / file);
-  GRUT_ASSERT_EQUAL( "/home/.grive", config.ConfigFile().string());
+	fs::path path("/home");
+	fs::path file(".grive");
+	Config config(path / file);
+	GRUT_ASSERT_EQUAL( "/home/.grive", config.Filename().string());
 }