cbstats usage has changed in 1.8.1 ( user needs to specify bucket username and password by using -b -p )

new usage :

farshid-mac:management farshid$ ./cbstats -h
Usage: cbstats [options]

Options:
-h, --help show this help message and exit
-a iterate over all buckets (requires admin u/p)
-b BUCKETNAME the bucket to get stats from (Default: default)
-p PASSWORD the password for the bucket if one exists