chk_and_link() { [ -e $1 ] || ln -s $2 $1; }
kill_link() { [ "$(readlink $1)" = "$2" ] && rm $1; }

post_install()
{
  chk_and_link /usr/sbin/sendmail /usr/bin/esmtp
  chk_and_link /usr/lib/sendmail /usr/bin/esmtp
  chk_and_link /usr/bin/mailq /usr/bin/esmtp
  chk_and_link /usr/bin/newaliases /usr/bin/esmtp

  chk_and_link /usr/share/man/man1/sendmail.1.gz esmtp.1.gz
  chk_and_link /usr/share/man/man1/mailq.1.gz esmtp.1.gz
  chk_and_link /usr/share/man/man1/newaliases.1.gz esmtp.1.gz
}

post_upgrade()
{
    post_install
}

pre_remove()
{
  kill_link /usr/sbin/sendmail /usr/bin/esmtp
  kill_link /usr/lib/sendmail /usr/bin/esmtp
  kill_link /usr/bin/mailq /usr/bin/esmtp
  kill_link /usr/bin/newaliases /usr/bin/esmtp

  kill_link /usr/share/man/man1/sendmail.1.gz esmtp.1.gz
  kill_link /usr/share/man/man1/mailq.1.gz esmtp.1.gz
  kill_link /usr/share/man/man1/newaliases.1.gz esmtp.1.gz
}

op=$1
shift
$op $*