Allow tail to display data after stream stops sending input after N seconds

[konsolebox]

A command like this doesn't display data:

tail -f /var/log/messages -n +1  | grep -e something --line-buffered | tail

probably because the last tail waits for the pipe to terminate.

But this could work if there exists an option like -S which allows
tail to wait for N seconds before considering input as "stopped" and
then displaying currently absorbed input.

Current workaround would be to use a temporary file and use sleep or
maybe some repeated inotify checks before running second tail but it's
messy.

-- 
konsolebox