Wikimedia Bugzilla is closed!

First case --create:

php SMW_conceptCache.php --create --concept=XYZ

Creating/updating concept caches. Use CTRL-C to abort.

Creating cache for "Concept:XYZ" ...
  No concept description found.

Done.

As a result --status shows that no cache is available.


Second case --delete:

# php SMW_conceptCache.php --delete --concept=XYZ

Deleting concept caches.

Abort with CTRL-C in the next 9 seconds ... 0
Deleting cache for "Concept:XYZ" ...

Done.

As a result --status shows that the cache is still available.