Only subscribed groups that occur in the current presentation sequence are rewound. That means that if no group arguments are specified, all groups occurring in the sequence defined in the init file will be rewound. Otherwise, only the groups specified on the argument line will be rewound.
When a group is rewound, the information about selections, partially read digests etc. are discarded. It will print notifications about this unless the -Q (quiet) option is used.
If the -i (interactive) option is specified, nngoback will report for each how many articles can be marked unread, and ask for confirmation before going back in that group.
If the -v (verbose) option is specified, nngoback will report how many articles are marked unread.
If the -N (no-update) option is specified, nngoback will perform the entire goback operation, but not update the .newsrc file.
If you are not up-to-date with your news reading, you can also use nngoback to catch up to only have the last few days of news waiting to be read in the following way:
nn -a0
nngoback 3
The nn command will mark all articles in all groups as read (answer all to the catch-up question.) The following nngoback will then make the last three days of news unread again.
Examples:
You cannot go more than 14 days back with nngoback. (You can change this limit as described below.)
Optionally, the back_act program accepts a single numerical argument specifying how many copies of the active file it should maintain. This is useful if news is expired after 7 days, in which case keeping more than 7 days of active file copies is wasteful.
~/.newsrc The record of read articles.
~/.newsrc.goback The original rc file before goback.
$db/active.N The N days `old' active file.
$master/back_act Script run by cron to maintain old active files.
The days are counted relative to the time the active files were copied.