How to apt-get from preseed/late_command?

[Josef Wolf <jw@raven.inka.de>]

Hello!

I'd like to "apt-get update; apt-get upgrade" from preseed/late_command
causing the first reboot to come up with updated kernel/modules.  So I
put this (splitted and commented for readability) into my seed file:

  d-i preseed/late_command string \
    cp /cdrom/preseed/postinstall.sh /target; \
    ln -s /postinstall.sh /target/etc/rcS.d/S98postinstall; \
    chroot /target apt-get --yes --force-yes -q update; \
    chroot /target apt-get --yes --force-yes -q upgrade; \
    echo press ENTER; read a

But for some reason, apt-get just hangs.  How can I find out the reason
why it hangs?  Any ideas?

BTW: Is there any reason that automatic update/upgrade at the end of the
     install is not done in the official distribution?