I've seen numerous posts on permissions, most of which amount to the same responses. 777, 775, 664, etc.
I think we (they, us) are ignoring the more common aspect of this question, that is, why is PHP having trouble writing /updating files?, because in the end, we are working in an admin that is built on top of a deployed piece of software, namely WordPress. WordPress is written in php, and has admin/public interfaces to manage these updating issues for us. It's the authors and developers of the WordPress program that have provided these interfaces, writing the backend functionality using a programming language, php, which, assumming it is installed correctly, has the ability to read/write/delete/create files, access databases, etc.
My point being, it's not YOUR USER that's attempting to write or update a file. It's the PHP executable, which has permissions to modify files. Now, when your discussing access via an FTP user, which has specific system permissions, then YES, these permission become relevant. But many of these permission questions are actually WordPress architecture issues, as I see it.
Does anyone agree?
As an example, many of you are familiar with FLICKR.com.
I have a user account on FLICKR.
I can upload and delete photos via this applications user interface.
My FLICKR user certainly has no permissions to do any of the above via FTP access to the FLICKR web servers.
Am I striking any chords here?
Am I missing something, or shouldn't my WordPress ADMIN user, which has access to edit/update type interfaces, be able to use these interfaces to perform the allowed functions? Why should I care about a server's file permissions. Technically, I shoudn't need access to the server at all once the appliation has been installed. I'm sure many WordPress users DO NOT have access to their web servers.