On Fri, Dec 29, 2023 at 10:56:52PM +1300, Richard Hector wrote:
> find $dir -mtime +7 -delete
"$dir" should be quoted.
> Will that fail to delete higher directories, because the deletion of files
> updated the mtime?
>
> Or does it get all the mtimes first, and use those?
It doesn't delete directories recursively.
unicorn:~$ mkdir -p /tmp/foo/bar
unicorn:~$ touch /tmp/foo/bar/file
unicorn:~$ find /tmp/foo -name bar -delete
find: cannot delete ‘/tmp/foo/bar’: Directory not empty
But I suppose you're asking "What if it deletes both the file and the
directory, because they both qualify?"
In that case, you should use the -depth option, so that it deletes
the deepest items first.
unicorn:~$ find /tmp/foo -depth -delete
unicorn:~$ ls /tmp/foo
ls: cannot access '/tmp/foo': No such file or directory
Without -depth, it would try to delete the directory first, and that
would fail because the directory's not empty.
-depth must appear AFTER the pathnames, but BEFORE any other arguments
such as -mtime or -name.
> And how precise are those times? If I'm running a cron job that deletes
> 7-day-old directories then creates a new one less than a second later, will
> that reliably get the stuff that's just turned 7 days old?
The POSIX documentation describes it pretty well:
-mtime n The primary shall evaluate as true if the file modification
time subtracted from the initialization time, divided by
86400 (with any remainder discarded), is n.
To qualify for -mtime +7, a file's age as calculated above must be at
least 8 days. (+7 means more than 7. It does not mean 7 or more.)
It's not uncommon for the POSIX documentation of a command to be superior
to the GNU documentation of that same command, especially a GNU man page.
GNU info pages are often better, but GNU man pages tend to be lacking.
