By default, vacation will notify any given sender about your status only once each week. If you plan to be gone longer, you can, as a courtesy, notify senders less often. To change this interval you can specify a new one using the -r switch when the database is initialized:

% /usr/ucb/vacation -r 31

The argument to the -r command-line switch is the number of days to wait between notifications. The interval is set, and vacation exits. The new wait interval remains in effect until the next time you set it, or until you clear the database with -i. There is no way to see what the setting currently is, so, if in doubt, reset it to a value you want.

Three special cases exist for the argument to -r. If the argument is not a number, the interval is set to an essentially infinite interval. If the argument is larger than the maximum value of a signed long integer on your system, the vacation program will print a usage message and exit. Finally, if the argument is zero, all interval waits are disabled and every message from a user gets a reply. Needless to say, this latter circumstance should be avoided.