--- |Indicates that the command-line arguments could not be parsed.
-exit_args_parse_failed :: Int
-exit_args_parse_failed = 1
+
+-- | No usernames found on either the command-line or in a config
+-- file.
+exit_no_usernames :: Int
+exit_no_usernames = 1
+
+
+-- | When running as a daemon, the existence of a fixed PID file is
+-- used to determine whether or not the daemon is already
+-- running. If the PID file already exists, we shouldn't start.
+--
+exit_pidfile_exists :: Int
+exit_pidfile_exists = 2