void-packages/srcpkgs/initramfs-tools/INSTALL

chrooted() {
	# borrowed from udev's postinst
	if [ "$(stat -c %d/%i /)" = "$(stat -Lc %d/%i /proc/1/root 2>/dev/null)" ]; then
		# the devicenumber/inode pair of / is the same as that of
		# /sbin/init's root, so we're *not* in a chroot and hence
		# return false.
		return 1
	fi
	return 0
}

case "${ACTION}" in
pre)
	# First time install.  Can we autodetect the RESUME partition?
	if [ -r /proc/swaps ]; then
		RESUME=$(tail -n $(($(wc -l /proc/swaps | awk ' { print $1 } ') - 1)) \
			/proc/swaps | sort -rk3 | head -n 1 | awk ' { print $1 } ')
		if command -v vol_id >/dev/null 2>&1; then
			UUID=$(vol_id -u "$RESUME" || true)
		elif [ -x /lib/udev/vol_id ]; then
			UUID=$(/lib/udev/vol_id -u "$RESUME" || true)
		fi
		if [ -n "$UUID" ]; then
			RESUME="UUID=$UUID"
		fi
	fi

	# write conf.d/resume if not in a chroot
	if [ -n "${RESUME}" ] && ! chrooted; then
		mkdir -p /etc/initramfs-tools/conf.d
		echo "RESUME=${RESUME}" > /etc/initramfs-tools/conf.d/resume
	fi
	;;
esac