title: undefined reference with boost when I try to compile
body: <p>i have lot of errors when i try to compile my server with boost.
  Here, this is my makefile :</p>
  
  <pre><code>NAME    =       serveur
  
  SRCS    =       Serveur/main.cpp                \
                  Serveur/Client.cpp              \
                  Serveur/Commande.cpp            \
                  Serveur/My_exception.cpp        \
                  Serveur/Network.cpp             \
                  Serveur/Server.cpp
  
  #####################################################                                                                                                                                                          
  
  OBJS                    =       $(SRCS:.cpp=.o)
  CC                      =       g++
  RM                      =       rm -f
  CFLAGS                  =       -g -W -Wall -Werror
  INCL                    =       ./Serveur/boost_1_47_0
  LIB                     =       ./Serveur/boost_1_47_0/stage/lib/
  NLIB                    =       -lboost_system -lboost_system-mt -lboost_filesystem -lboost_filesystem-mt
  
  #####################################################                                                                                                                                                          
  
  $(NAME) :       $(OBJS)
          @$(CC) $(OBJS) -I$(INCL) -L$(LIB) $(NLIB) -o $(NAME)
          @printf "\n \033[33m[Message]\033[39m Compilation under Linux done\n\n"
  
  .cpp.o  :
          @$(CC) $(CFLAGS) -I$(INCL) -L$(LIB) $(NLIB) -c $&lt; -o $@
          @printf " \033[34m[Compilation]\033[39m %s\n" $&lt;
  
  re      :       fclean all
  
  all     :       $(NAME)
  
  clean   :
          @$(RM) *~ $(OBJS)
          @printf " \033[31m[Delete] \033[39m%s\n" $(OBJS)
  
  fclean  :       clean
          @$(RM) $(NAME)
          @printf "\n \033[31m[Delete] \033[39m%s\n\n" $(NAME)
  </code></pre>
  
  <p>After "googling" i found that it's necessary to put <code>-lboost_filesystem</code> but it's not working again and there are next errors :</p>
  
  <pre><code>Serveur/main.o: In function `__static_initialization_and_destruction_0':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:214: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:215: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:216: undefined reference to `boost::system::system_category()'
  Serveur/main.o: In function `error_code':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:315: undefined reference to `boost::system::system_category()'
  Serveur/main.o: In function `boost::asio::error::get_system_category()':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/asio/error.hpp:216: undefined reference to `boost::system::system_category()'
  Serveur/Client.o: In function `__static_initialization_and_destruction_0':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:214: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:215: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:216: undefined reference to `boost::system::system_category()'
  Serveur/Network.o: In function `__static_initialization_and_destruction_0':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:214: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:215: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:216: undefined reference to `boost::system::system_category()'
  Serveur/Server.o: In function `__static_initialization_and_destruction_0':
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:214: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:215: undefined reference to `boost::system::generic_category()'
  /home/abad_a//rendulocal/tech3/cpp/babel-2014-abad_a/Serveur/./Serveur/boost_1_47_0/boost/system/error_code.hpp:216: undefined reference to `boost::system::system_category()'
  collect2: ld returned 1 exit status
  make: *** [serveur] Error 1
  </code></pre>
  
  <p>Anyone know why it's not working?</p>