-h, --help Show help options
-c, --config=FILE Use configuration file
-d, --debug Print debugging messages
--test-mode Run as unprivileged user, skipping things that require root access
--pid-file=FILE File to write PID into
--xsessions-dir=DIRECTORY Directory to load X sessions from
--xgreeters-dir=DIRECTORY Directory to load X greeters from
--log-dir=DIRECTORY Directory to write logs to
--run-dir=DIRECTORY Directory to store running state
--cache-dir=DIRECTORY Directory to cached information
-v, --version Show release version
/etc/lightdm/lightdm.conf Configuration
/etc/lightdm/users.conf User list configuration (if not using Accounts Service)
/etc/lightdm/keys.conf XDMCP keys
dm-tool (1)