-since option for ls -lt

[Steve Summit]

Two additional points:

     1.	Beware that find -newer is slightly buggy; the
	implementation is simpleminded and can only handle a
	single -newer.  Therefore, something like

		find -newer oldfile ! -newer newfile -print

	(which wasn't implied by the original question, but which
	I've occasionally wanted to use) doesn't work.  (It ought
	to print the names of those files newer than oldfile but
	not newer than newfile, i.e. a range.)  I've fixed this;
	I don't remember if I posted the fixes (or indeed even
	the bug).

     2.	There are (probably nonstandard) versions of test that
	can do

		test file1 -nt file2
	and
		test file1 -ot file2

	("newer than" and "older than").

                                            Steve Summit
                                            scs at adam.pika.mit.edu