prerm is in lua5.2 5.2.4-1ubuntu1.
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 | #!/bin/sh -e
case "$1" in
    remove)
        update-alternatives --remove lua-interpreter /usr/bin/lua5.2
        update-alternatives --remove lua-compiler /usr/bin/luac5.2
        ;;
esac
 |