10Dec/081
How To Upgrade WordPress on CentOS 5 From A Shell
Below are the commands that I used to upgrade WordPress to version 2.8 on a CentOS 5.2 installation, hopefully you will find this helpful. Always be sure to backup your database and any customizations before you upgrade. I would suggest using WordPress Database Backup it makes things easy.
cd /tmp
wget http://wordpress.org/latest.tar.gz
tar -zxvf latest.tar.gz
rm -rf /var/www/wordpress/wp-includes
rm -rf /var/www/wordpress/wp-admin
cd /var/www/wordpress
/bin/cp -rf /tmp/wordpress/* .
Once you have done this go to http://yourdomain.com/wp-admin/upgrade.php and click the upgrade database button and you should be good to go. Once you have completed the upgrade it would be a good idea to backup your database again.