动态链接库 路径配置

使用动态链接库的时候经常挂不上，出现类似下面的错误：

error while loading shared libraries: libgsl.so.19: cannot open shared object file: No such file or directory

有两种解决方安：
（1）配置环境变量

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
export LD_LIBRARY_PATH

（2）修改系统动态链接库配置

Review your /etc/ld.so.conf. If /usr/local/lib is not listed there, add it. Now, run ldconfig to detect the shared object file and add it to some system-wide index.