preinst is in friendly-recovery 0.2.25.
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
set -e
# Automatically added by dh_installinit
if [ "$1" = install ] || [ "$1" = upgrade ]; then
	if [ -e "/etc/init.d/friendly-recovery" ] && [ ! -L "/etc/init.d/friendly-recovery" ]; then
		if [ "`md5sum \"/etc/init.d/friendly-recovery\" | sed -e \"s/ .*//\"`" != \
		     "`dpkg-query -W -f='${Conffiles}' friendly-recovery | sed -n -e \"\\\\' /etc/init.d/friendly-recovery '{s/ obsolete$//;s/.* //p}\"`" ]
		then
			echo "Obsolete conffile /etc/init.d/friendly-recovery has been modified by you, renaming to .dpkg-bak"
			mv -f "/etc/init.d/friendly-recovery" "/etc/init.d/friendly-recovery.dpkg-bak"
		else
			rm -f "/etc/init.d/friendly-recovery"
		fi
	fi
fi
# End automatically added section
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