nginx启动fastdfs时，报unknown directive "ngx_fastdfs_module"

我照着教程，添加了fastdfs模块，但是一直不成功，看了一下nginx-errors.log：

2019/12/30 10:44:52 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:30
2019/12/30 10:48:16 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:30
2019/12/30 10:51:46 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:30
2019/12/30 11:05:50 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:30
2019/12/30 11:11:30 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:31
2019/12/30 12:31:30 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:31
2019/12/30 12:37:28 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:31
2019/12/30 13:50:38 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:31
2019/12/30 14:22:34 [emerg] 6399#0: unknown directive "ngx_fastdfs_module" in /opt/nginx/conf/sites-enabled/ip.conf:31

发现了以上错误，请问该怎么解决？