11 获取文件的绝对路径

1. linux api ```cpp char path[1024] = {0};

realpath(“../src/dict.h”, path); std::cout << path << std::endl; // output /data/redis-master/src/dict.h

realpath(“.”, path); std::cout << path << std::endl; // output /data/redis-master/demos

realpath(“../../../“, path); std::cout << path << std::endl; // output / ```