How to check which file is older

Question

Is there a command in Mathematica to check the date when a file was last modified? Suppose I have two notebooks: File1.nb and File2.nb, I need a way to find out which notebook is older. If no such command exists is there a way to do this in Mathematica regardless of the operating system we are working on?

Answer 1

You are looking for FileDate.

Answer 2

Here are some commands I ran on my machine to generate a few files, and give them some history:

touch foo1 foo2 foo3 foo4
touch foo3
cat foo2

Here are the files:

files = FileNames["foo*"]

(*
==> {"foo1", "foo2", "foo3", "foo4"}
*)

The most recently changed file:

SortBy[files, FileDate] // Last

(*
==> "foo3"
*)

The newest file:

SortBy[files, FileDate[#, "Creation"] &] // Last

(*
==> "foo4"
*)

The most recent file that was looked at:

SortBy[files, FileDate[#, "Access"] &] // Last

(*
==> "foo2"
*)