preinst is in libzookeeper-mt-dev 3.4.8-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | #!/bin/sh
set -e
case "$1" in
  install|upgrade)
    DOCDIR=/usr/share/doc/libzookeeper-mt-dev
    if [ -L $DOCDIR ]; then
      rm $DOCDIR
    fi
  ;;
esac
exit 0
 |