postrm is in fai-nfsroot 5.0.3ubuntu1.
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 | #!/bin/sh -e
case "$1" in
    remove)
        rm -f /etc/init.d/rcS
        dpkg-divert --package fai-nfsroot --remove --rename /etc/init.d/rcS
        ;;
    purge)
        update-rc.d fai-abort remove > /dev/null
        ;;
esac
exit 0
 |