getting the mdate of a file

[David Bear]

I'd like to run tar using a data incremental.  For example, if I run
tar today like this:
  tar cvf /dev/nsa0 /home > home.catalog

I end up with a listing of all files tarr'ed in home.catalog.  Then
the next day I'd like to run tar but only have tar select files that
were changed since home.catalog was written.  Tar has --newer DATE
option but I would like to set the DATE according to the last modified
time of the home.catalog.

So, question 1 is how do I get the last mod date of a file?  

Question 2 is, is there a better way that I'm missing?

-- 
David Bear
phone: 	480-965-8257
fax: 	480-965-9189
College of Public Programs/ASU
Wilson Hall 232
Tempe, AZ 85287-0803
 "Beware the IP portfolio, everyone will be suspect of trespassing"