The first is dynamic link library, please refer to https://blog.csdn.net/lucky_ huijun/article/details/105165359

The second is that there is no correct input path name. The following is wrong

spawn-fcgi -a 127.0.0.1 -p 9001 -f a.out

The right thing to do is

spawn-fcgi -a 127.0.0.1 -p 9001 -f /a.out

If it’s the second mistake, slap yourself^_^