## tidy loose ends...
set -e
# fix mark auto-installed essential packages and their dependencies
_pkgdeps(){ set -e
	chroot /target dpkg-query -Wf=',${Pre-Depends},${Depends},${Recommends}\n' $* 2>/dev/null|sed -r -e 's/[,|] *([a-z0-9.+-]+)?(:\s+)?( *[^|,]*)?/\1\n/g'|sed '/^$/d'|sort -u; }
_pkg2re(){ set -e
	echo $*|sed -r -e 's/\s+/\|/g;s/^\|//;s/([.+-])/\\\1/g;s/\|$//'; }
_pkgreal(){ set -e
	chroot /target dpkg-query -Wf='${Package},${Provides},\n'|sed -r "/,,/d;s/^([a-z0-9.+-]+).*[,|] *($(_pkg2re $*))[ :,]/\1/;/,/d"; }
_pkganddeepdeps(){ set -e
	local rest=$*
	local all=$rest
	for i in 1 2 3 4 5
	do local deps=$(_pkgdeps $rest)
		rest="$deps $(_pkgreal $deps)"
		all="$all $rest"
	done
	echo $all|sed -r 's/\s+/\n/g'|sort -u; }
essentials=$(chroot /target dpkg-query -Wf='${Package}%${Essential}\n'|sed -r 's/(.*)%yes/\1/;/%/d')
chroot /target apt-mark auto $(_pkganddeepdeps $essentials apt linux-image-*)
# fix mark auto-installed d-i installed packages unusable on their own
chroot /target apt-mark auto aptitude-common grub-common isc-dhcp-common tasksel-data vim-common

# keep backup of any tweaked (i.e. edited or created) config file
_backup(){ set -e
	[ -e "$1.orig" ] || if [ -e "$1" ]; then cp -a "$1" "$1.orig"
	else touch "$1.orig"
	fi; }
_clone(){ set -e
	_backup "$2"
	cp -a "$1" "$2"; }
_setvar(){ set -e
	_backup "$1"
	sed -i -r -e "s,^#?($2)=.*,\\1=$3," "$1"; }

## non-technical operation
# auto-repair inconsistent filesystems during boot
_setvar /target/etc/default/rcS FSCKFIX yes