Hi Alex, On Sat, Apr 16, 2011 at 09:55:48PM -0700, Alex Chen wrote: > After I set the compiler flag, I get the following compilation error: > Building file: /home/Projects/Cache.cpp > Invoking: GCC C++ Compiler > g++ -I"/home/Projects/include" -O0 -g3 -Wall -c -fmessage-length=0 > -Wno-pragmas -m64 -fPIC -R"/usr/local/lib" -MMD -MP -MF"Cache.d" > -MT"Cache.d" -o"Cache.o" "/home/Projects/Cache.cpp" > g++: unrecognized option '-R/usr/local/lib' > (Whether there is a space between -R and /usr/local/lib does not matter, > they all produce the error.) > > If I use that flag for the linker, I get a different linker error: > Building target: libC.so > Invoking: GCC C++ Linker > g++ -L"/home/alexchen/Projects/lib" -R/usr/local/lib -shared -o"libC.so" > ./Disk.o ./Cache.o -luuid -latomic_ops > g++: unrecognized option '-R/usr/local/lib' > Finished building target: libC.so > > By the way, I am using Eclipse C++ plug-in so the flag is set via the > project's compiler/linker 'Miscellaneous' setting. You passed the "-R" to the compiler, but you should pass it to the linker. Also in the second example: "g++" ist NOT the linker (it will call the linker "ld" itself). So to correct the problem: you have to tell the compiler that "-R/usr/local/lib" is an option for the linker. That is done using "-Wl,..." So, the command g++ -I"/home/Projects/include" -O0 -g3 -Wall -c -fmessage-length=0 -Wno-pragmas -m64 -fPIC -Wl,-R"/usr/local/lib" -MMD -MP -MF"Cache.d" -MT"Cache.d" -o"Cache.o" "/home/Projects/Cache.cpp" should work. (See also http://gcc.gnu.org/faq.html#rpath) Axel > > > On 4/16/2011 8:54 PM, Alex Chen wrote: >> Thanks for the information, Dr. Kirby. >> Is that -R flag for the compiler or the linker? >> I thought the linker's -L flag will tell it to look for libraries there. I >> guess it does not embed the path in the final library file. >> >>> >>> The issue is that the run time linker does not know to look in >> /usr/local/lib for >>> libraries, so unless the path is hard-coded into the executable, the >> libraries >>> will not be found. >>> >>> Some programs are compiled in such a way they automatically look in >>> /usr/local/lib. You should find that by recompiling all your sources with >> the >>> compiler flag "-R /usr/local/lib" will work. >>> >>> Setting >>> >>> LD_LIBRARY_PATH=/usr/local/lib >>> export LD_LIBRARY_PATH >>> >>> will probably "solve" your problem, in that your code will probably find >> the >>> libraries. But it's not a very good solution. >>> >>> You can change the places the run time linker looks for libraries. You >> could >>> make it always look in /usr/local/lib, but such a change is a bad idea >> IMHO. >>> Dave >> >
