mq함수류 오류 해결

posix_msg.o: In function `main':

posix_msg.c:(.text+0xb5): undefined reference to `mq_unlink'

posix_msg.c:(.text+0xe2): undefined reference to `mq_open'

posix_msg.c:(.text+0x1de): undefined reference to `mq_close'

posix_msg.o: In function `start_msq_sender':

posix_msg.c:(.text+0x334): undefined reference to `mq_send'

posix_msg.o: In function `start_msq_receiver':

posix_msg.c:(.text+0x37d): undefined reference to `mq_getattr'

posix_msg.c:(.text+0x3bb): undefined reference to `mq_receive'

빌드시 -l(라이브러명) 

ex) # gcc -o mq_test mq_test.c -lpthread -lrt