As the title states, how do I check if a plugin is loaded?
When I hit tab (for SuperTab) all I get is the ordinary character "tab" inserted in my file and when I hit ctrl-space I just get thrown out of insert-mode (same behavior as hitting ESC)
The :scriptnames command lists all scripts that have been sourced; check for the plugin name in its output. If it's missing, it is either due to a wrong installation or because 'runtimepath' is incorrect.
Alternatively, if you know the mapping a plugin should define
:verbose imap <Tab>
will show the mapping and from which script is was set.
Programmatically, it is best to check for the canonical include guard if exists('g:loaded_pluginname') or for a defined command via if exists(':PluginCommand').
来源：https://stackoverflow.com/questions/13179582/how-to-check-if-supertab-and-jedi-vim-is-activated