How to run drush command from code

I'd like to trigger a D开发者_运维问答rush command from a Drupal function, anyone have any suggestions for how best to do it?

Some drush commands are just making calls to standard Drupal functionality, so you could dig and find that function and call it. If you have a specific command, ask and I am sure someone will help.

Some of the other things drush does, like downloading modules, are probably best left there, as they are high level administrative functions. What is the end goal you are trying to achieve?