source: udev/boot.udev@ f8736bc

#!/bin/sh
########################################################################
# Begin $rc_base/init.d/udev
#
# Description : Udev Boot Script
#
# Authors     : Based on Open Suse Udev Rules
#               kay.sievers@suse.de
#
# Adapted to  : Jim Gifford
# LFS
#
# Version     : 00.00
#
# Notes       :
#
########################################################################

. /etc/sysconfig/rc
. ${rc_functions}

PATH="/sbin:/bin"
DAEMON=/sbin/udevd
udevd_args="--daemon"

function trigger_device_events() {
        # generate events with the sysfs trigger
        list=$(echo /sys/bus/*/devices/*/uevent)
        list="$list $(echo /sys/class/*/*/uevent)"
        list="$list $(echo /sys/block/*/uevent /sys/block/*/*/uevent)"
        for i in $list; do
            case "$i" in
                */device/uevent)
                    # skip followed device symlinks
                    continue
                    ;;

                */class/mem/*|*/class/tty/*)
                    first="$first $i"
                    ;;

                */block/md*)
                    last="$last $i"
                    ;;

                */*)
                    default="$default $i"
                    ;;
            esac
        done

        # trigger the sorted events
        for i in $first $default $last; do
            echo "add" > "$i"
        done
}

case "$1" in
    start)

        # disable hotplug helper, udevd listens to netlink
        echo "" > /proc/sys/kernel/hotplug

        # start udevd
        boot_mesg "Starting udevd"
        loadproc $DAEMON $udevd_args

        # cleanup some stuff
        rm -rf /events/*

        # unlikely, but we may be faster than the first event
        mkdir -p /dev/.udev/queue

        # configure all devices
        trigger_device_events

        # until we know how to do better, we wait for all events to finish
        loop=0
        while test -d /dev/.udev/queue; do
            sleep 0.1;
            test "$loop" -gt 300 && break
            loop=$(($loop + 1))
        done
        ;;

    stop)
        boot_mesg "Stopping udevd:"
        echo "/sbin/hotplug" > /proc/sys/kernel/hotplug
        killproc $DAEMON
        ;;

    restart)
        ${0} stop
        sleep 1
        ${0} start
        ;;

    status)
        statusproc /sbin/udevd
        ;;

    reload)
        boot_mesg "Reloading udev rules:"
        udevcontrol reload_rules
        cp --preserve=all --recursive --update /lib/udev/devices/* /dev
        evaluate_retval
        ;;

    force-reload)
        boot_mesg "Updating all available device nodes in /dev: "
        udevcontrol reload_rules
        rm -rf /dev/.udev /dev/disk
        cp --preserve=all --recursive --update /lib/udev/devices/* /dev
        trigger_device_events
        evaluate_retval
        ;;
    *)
        echo "Usage: $0 {start|stop|restart|status|reload|force-reload}"
        exit 1
        ;;
esac