preinst is in libtiffxx0c2 3.9.5-2ubuntu1.
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 | #!/bin/sh
set -e
if [ "x$1" = "xupgrade" -a \
-d /usr/share/doc/libtiffxx0c2 -a ! -h /usr/share/doc/libtiffxx0c2 ]; then
rm -rf /usr/share/doc/libtiffxx0c2
fi
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