Drush cc all 'Killed' With a D6 instllation I am seeing 'Killed' returned whenever I try to clear the Drupal cache.

Verbose output gives me this:

Initialized Drupal 6.30 root directory at /var/www [notice]
Intialized Drupal site default at sites/default [notice]
Undefined variable: may_cache feed_field.module 12 [notice]
Killed
The string "Killed" doesn't exist in the Drupal 6.30 codebase.

You might have a custom/contrib module which is responsible, or perhaps a Drush extension.

If that's the case, to find it:

grep -nr "Killed" /path/to/drupal/root
grep -nr "Killed" /path/to/drush/extension/folder


(The extension path will probably be ~/.drush)