You can disable all WordPress plugin at once from a single MySQL query. This will be faster to disable all plugins through command line. You need to disable plugins if you want upgrade the WordPress site. Following MySQL command will helpful for you.
UPDATE wp_options SET option_value = '' WHERE option_name = 'active_plugins';
Above command will replace the active_plugins’s field value to a blank string. Which means all plugins of that site will be disabled in site backend. Dont’ worry plugins folder still presents in theme directory ,because above command do not delete the plugin folder.