nginx一个fastcgi的demo错误

2016/03/23 18:29:22 [error] 3556#0: *6 upstream prematurely closed FastCGI stdout while reading response header from upstream, client: 127.0.0.1, server: localhost, request: "GET /main.cgi HTTP/1.1", upstream: "fastcgi://127.0.0.1:8081", host: "127.0.0.1".

一直都是OK 的，突然改了一下代码就乱了，实在不明白，检查了半天，才发现，原来我把 HTTP头输出给屏蔽掉了，也是醉了

n = sprintf(sendline,"Content-type: text/html "
                " "
                "<title>FastCGI Hello!</title>"
                "<h1>FastCGI Hello!</h1>"
                "Request number %d running on host <i>%s</i> ",
                ++count, getenv("SERVER_NAME"));


                printf("%s",sendline);

一定要先输出头，否则nginx会直接屏蔽