In order to show $_FILES or $_POST, you will need to create a sumbenu_page under the post_type. Then, you will be able to manipulate $_FILES and $_POST in whichever way you want. This means that upload_screen() function should be a submenu page.
saving file to external server vip
Making a custom upload form and page in the admin section
get_attached_file() can do this, given you know attachment ID for input.
Folder Permissions + Security Concerns
Victor, Maybe this is helping you. http://goo.gl/9sahyp Regards, Hugo
Using external file with WP_USE_THEMES set to false causing 404
No you don’t, and not even sure if you can use it for listing files in directories. The only limitation on reading files is that they will be readable to the web server, and obviously plugin directories has to be readable for the web server to be able to read the PHP files. Now, if … Read more
In short: YES, is a big time threat. Explained: Little time has passed since I asked this question but now I have found that the safer and most useful file permissions for wordpress are the following: Directories: 755 Owner can: Read, write and execute. Group and public can: Read and execute. Read-only files:644 Owner can: … Read more
FS method direct on NGINX