solve codeigniter 404 error in Nginx

pathinfo

##########################################pathinfo 模式
set $path_info "";
set $real_script_name $fastcgi_script_name;
if ($fastcgi_script_name ~ "^(.+?\.php)(/.+)$"){
     set $real_script_name $1;
     set $path_info $2;
}
include fastcgi.conf;
fastcgi_param SCRIPT_FILENAME $document_root$real_script_name;
fastcgi_param SCRIPT_NAME $real_script_name;
fastcgi_param PATH_INFO $path_info;
##########################################nginx支持pathinfo 模式的重点