Replying way late here, but FastCGI doesn't work by printing to stdout, it talks to a domain socket or an open TCP port. The grandparent post was asking "why c

Replying way late here, but FastCGI doesn't work by printing to stdout, it talks to a domain socket or an open TCP port. The grandparent post was asking "why can't lambda just use stdout?" The magic of TCP or domain sockets is that calling accept() gives you a unique file descriptor that corresponds with a single client. Just using stdout doesn't work that way, unless your entire process was launched to handle one request, hence CGI being very inefficient.