Fixing file paths after a change in location of a site's files directory

If, like Agaric, you're moving from multisite to separate installations for each site (or vice versa) you may find your user-uploaded file paths changing. Drag.

The solution is updating your database, and you can replace part of the file path with straight SQL:

UPDATE files SET filepath = REPLACE(filepath, "sites/help4computers.com/files/", "sites/default/files/")

To do this using the command line, you simply need your database information:

You can get your database username and password from your Drupal site's settings.php

It's the part in the $db_url = line that looks like:
example:EvC.aRxhbmPnrLd3
@localhost/help4computers

help4computers:BvC.aRxdbmBnrad3@localhost/help4computers

Agaric Asides

I thought Pathologic might be a fix to my problems here, but it most certainly is not: it is an input filter and acts on links in content, and not on attached files.

Also of (potential) interest:

http://drupal.org/project/uploadpath

http://agaricdesign.com/note/drupal-function-give-path-files-directory

Resolution