Seconds since Epoch as ten decimal digits

Folks,

As many of you know, most Unix variants store the number of
seconds since the epoch.  The GNU version of "date" has an
extension to display this value, as follows.

    $ date --help | grep %s ; date +%s
      %s   seconds since `00:00:00 1970-01-01 UTC' (a GNU extension)
    991282474

When will this number need ten decimal digits to display?

    $ perl -le'print"".localtime(10**9)'
    Sun Sep  9 11:46:40 2001

Unfortunately, this isn't a Humbug meeting :(

Yours sincerely,

-- Mark John Suter  | I know that you  believe  you understand
suter at humbug.org.au | what you think I said, but I am not sure
gpg key id F2FEBB36 | you realise that what you  heard  is not
mobile 0411 262 316 | what I meant.        Robert J. McCloskey