post_install(){
  groupadd -g 2000 virtuoso &>/dev/null
  useradd -u 2000 -g virtuoso -d /var/lib/virtuoso-opensource-7/db \
     -s /bin/false virtuoso &>/dev/null
}

post_upgrade(){
  getent group virtuoso >/dev/null 2>&1 || groupadd -g 2000 virtuoso &>/dev/null
  getent passwd virtuoso >/dev/null 2>&1 || useradd -u 2000 -g virtuoso \ 
    -d /var/lib/virtuoso-opensource-7/db -s /bin/false virtuoso &>/dev/null
}