WordPress metabox file upload in custom post [duplicate]

For WordPress metabox file upload in custom post. please refer Below link

http://code.tutsplus.com/articles/attaching-files-to-your-posts-using-wordpress-custom-meta-boxes-part-1–wp-22291

or you can use following plugins

https://wordpress.org/plugins/simple-fields/
http://www.advancedcustomfields.com/

both plugin best for custom field . you can also create reapeatable fields