For more info you can visit the knife configuration page on opscode
% knife --help
Usage: knife sub-command (options)
-s, --server-url URL Chef Server URL
-k, --key KEY API Client Key
--[no-]color Use colored output, defaults to enabled
-c, --config CONFIG The configuration file to use
--defaults Accept default values for all questions
-d, --disable-editing Do not open EDITOR, just accept the data as is
-e, --editor EDITOR Set the editor to use for interactive commands
-E, --environment ENVIRONMENT Set the Chef environment
-F, --format FORMAT Which format to use for output
-u, --user USER API Client Username
--print-after Show the data after a destructive operation
-V, --verbose More verbose output. Use twice for max verbosity
-v, --version Show chef version
-y, --yes Say yes to all prompts for confirmation
-h, --help Show this message