The files sup uses are pretty simple.
Under $base/${collection}/ there are two files, when.${release} and
last.${release}. $base is defined in your sup file /etc/supfiles/coll.list
under the line for ${collection} release=${release}.

To create last.pkgsrc:
find /usr/pkgsrc/. | egrep -v '/CVS' | \
	sed -e 's,/usr/pkgsrc/,,' -e 's,\./,,' > last.pkgsrc

when.pkgsrc contains a date (second past epoch) of when the files were
last updated.
to create it with todays date:
date '+%s' > when.pkgsrc

On Fri, 21 Jun 2002, Marton Fabo wrote:

> Date: Fri, 21 Jun 2002 01:19:07 +0200
> From: Marton Fabo <morton@eik.bme.hu>
> To: tech-pkg@netbsd.org
> Subject: pkgsrc - sup
>
>
> I hope you folks aren't yet annoyed by my silly questions... Well, now what
> I'm curious about is: I've installed pkgsrc on a machine by fetching the
> pkgsrc tarball from the netbsd.org ftp, and extracted it. According to the
> pkgsrc docs, I can keep it updated by sup; but if I try that, it'll request
> any changes since 1970 for the first time. The machine in question has a
> quite unstable internet connection, and any attempts so far to sup pkgsrc
> failed.
>
> So is there a way to fool sup into thinking that it has recently (when the
> stuff was installed) updated, and it should only request changes since then?
>
> thx mortee
>
>
>

Elfin