问个问题，为什么编译FastDFS会有pthread_kill 找不的哦啊的错误呢

qqliangqi

../common/sched_thread.o: In function `sched_start':
/home/night/fastDFS/FastDFS/tracker/../common/sched_thread.c:493: undefined reference to `pthread_create'
../common/pthread_func.o: In function `init_pthread_lock':
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:32: undefined reference to `pthread_mutexattr_init'
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:40: undefined reference to `pthread_mutexattr_settype'
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:57: undefined reference to `pthread_mutexattr_destroy'
../common/pthread_func.o: In function `init_pthread_attr':
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:84: undefined reference to `pthread_attr_getstacksize'
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:115: undefined reference to `pthread_attr_setstacksize'
../common/pthread_func.o: In function `create_work_threads':
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:156: undefined reference to `pthread_create'
../common/pthread_func.o: In function `kill_work_threads':
/home/night/fastDFS/FastDFS/tracker/../common/pthread_func.c:182: undefined reference to `pthread_kill'