prerm is in plymouth-theme-spinfinity 0.8.2-2ubuntu30.
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
set -e
if [ "x$1" = xremove ]; then
update-alternatives \
--remove default.plymouth /lib/plymouth/themes/spinfinity/spinfinity.plymouth
fi
|