Originally Posted by bakdong
If you actually want files that are exactly 7 days old from the current time, don't use daystart.
True. To clarify, using -daystart and -mtime 7 from today (2009-04-19) you will find files last modified between 2009-04-12 00:01 and 2009-04-13 00:00.
Without -daystart you have to consider files modified 7*24 hours ago from the current time, always in the range of 24 hours. Suppose now is 11:55, using only -mtime 7 you will find files modified between 2009-04-11 11:56 and 2009-04-12 11:55.