Installing and Upgrading Simple Machines Forum 2.0

Uncompress the 2.0-install package then the 2.0-upgrade package.
Change line number 25 on install.php, as there's a version error in the script, to:

$GLOBALS['current_smf_version'] = '2.0 RC1.2';

Change that following line on upgrade.php to RC1.2 from RC1-1:

define('SMF_VERSION', '2.0 RC1.2');

Then chmod the files:

chmod 777 attachments/ avatars/ cache/ Packages/ Packages/installed.list Smileys Themes agreement.txt Settings.php Settings_bak.php

Ideally, from a security standpoint, one should only do chmod 755 for directories and 644 for the user running the apache server, typically called "apache".
One can selectively set permissions this way using the following commands:

find /dir/to/chmod/all/dirs -type d -exec chmod 755 {} \; # recursively changing dir permissions, ';' is very important

Run the install.php file to setup the settings file, remember to choose UTF-8 for the database if you're using it and then stop the installation procedure. Use the repair_settings.php file before doing the upgrade. Some paths need to be fixed or there will be some errors which may make the upgrade unable to complete.

Reload the upgrade script when you see this error:

Error!
Duplicate entry '0' for key 1

As it doesn't seem to be important. Consulted with SMF developers before proceeding. The upgrade process should proceed from where it left off and no data should be lost.

If you're testing out the new installation in a different directory, go to the admin area and update all the paths of custom themes. Repair settings doesn't do this and the install can be made unworkable when installing mods in a test installation.