prerm is in libglib2.0-dev 2.56.1-2ubuntu1.
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 7 8 | #!/bin/sh
# libglib2.0-dev needs a prerm in buster, so that if the old prerm fails
# due to https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=887629 we can
# recover by running the new prerm. Keep this workaround until after
# Debian 10 has been released.
set -e
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