postrm is in scsitools 0.12-3ubuntu1.
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  | #!/bin/sh -e
if [ "$1" = "purge" ] ; then
	update-rc.d scsitools-pre.sh remove >/dev/null
	update-rc.d scsitools.sh remove >/dev/null
fi
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