systemd-stable/src/99-systemd.rules

#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.

ACTION!="add|change", GOTO="systemd_end"

KERNEL=="tty[0-9]|tty1[0-2]", TAG="systemd"
KERNEL=="ttyS*", TAG="systemd"

SUBSYSTEM=="block", KERNEL!="ram*|loop*", TAG="systemd"

# We need a hardware independent way to identify network devices. We
# use the /sys/subsystem path for this. Current vanilla kernels don't
# actually support that hierarchy right now, however upcoming kernels
# will. HAL and udev internally support /sys/subsystem already, hence
# it should be safe to use this here, too. This is mostly just an
# identification string for systemd, so whether the path actually is
# accessible or not does not matter as long as it is unique and in the
# filesystem namespace.
#
# http://git.kernel.org/?p=linux/hotplug/udev.git;a=blob;f=libudev/libudev-enumerate.c;h=da831449dcaf5e936a14409e8e68ab12d30a98e2;hb=HEAD#l742

SUBSYSTEM=="net", KERNEL!="lo", TAG="systemd", ENV{SYSTEMD_ALIAS}="/sys/subsystem/net/devices/%k"
SUBSYSTEM=="bluetooth", TAG="systemd", ENV{SYSTEMD_ALIAS}="/sys/subsystem/bluetooth/devices/%k"

SUBSYSTEM=="bluetooth", TAG="systemd", ENV{SYSTEMD_WANTS}="bluetooth.target"
SUBSYSTEM=="printer", TAG="systemd", ENV{SYSTEMD_WANTS}="printer.target"
ENV{ID_SMARTCARD_READER}=="*?", TAG="systemd", ENV{SYSTEMD_WANTS}="smartcard.target"

LABEL="systemd_end"