I am busy writing a plugin (called supermail), so I install, activate, deactivate, and delete the plugin fairly often. However, quite often one or more of these operations doesn't go smoothly, and I just manually delete the files. When I install the plugin again by uploading a zip file, called supermail.zip, I find the plugin installed under a directory called plugins/supermail1. I assume this is because WP still has a record of the plugin, somewhere in the DB, or even maybe just in session. Short of restarting Apache, is there anything I can do, both in my plugin code to help ensure this doesn't happen, and as administrator, to result the issue when it does happen?
wordpress plugin installer don't rename dir ever. It could be renamed in your zip. When directory already exists wordpress plugin installer just show the error plugin already exists.