CentOS RedHat启动过程

[root@sky etc]# cat inittab
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
#   0 - halt (Do NOT set initdefault to this)
#   1 - Single user mode
#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
#   3 - Full multiuser mode
#   4 - unused
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:5:initdefault:

[root@sky init]# cat rc.conf
# rc - System V runlevel compatibility
#
# This task runs the old sysv-rc runlevel scripts.  It
# is usually started by the telinit compatibility wrapper.
#
# Do not edit this file directly. If you want to change the behaviour,
# please create a file rc.override and put your changes there.

start on runlevel [0123456]

stop on runlevel [!$RUNLEVEL]

task

export RUNLEVEL
console output
exec /etc/rc.d/rc $RUNLEVEL
[root@sky init]#

[root@sky ~]# cat /etc/rc.d/rc  
#! /bin/bash
#
# rc            This file is responsible for starting/stopping
#               services when the runlevel changes.
#
# Original Author:       
#               Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org>
#

set -m

# check a file to be a correct runlevel script
check_runlevel ()
{
        # Check if the file exists at all.
        [ -x "$1" ] || return 1
        is_ignored_file "$1" && return 1
        return 0
}

# Now find out what the current and what the previous runlevel are.
argv1="$1"
set $(/sbin/runlevel)
runlevel=$2
previous=$1
export runlevel previous

. /etc/init.d/functions

export CONSOLETYPE
do_confirm="no"
if [ -f /var/run/confirm ]; then
        do_confirm="yes"
fi
UPSTART=
[ -x /sbin/initctl ] && UPSTART=yes
# See if we want to be in user confirmation mode
if [ "$previous" = "N" ]; then
        if [ "$do_confirm" = "yes" ]; then
                echo $"Entering interactive startup"
        else
                echo $"Entering non-interactive startup"
        fi
fi

# Get first argument. Set new runlevel to this argument.
[ -n "$argv1" ] && runlevel="$argv1"

# Is there an rc directory for this new runlevel?
[ -d /etc/rc$runlevel.d ] || exit 0

# Set language, vc settings once to avoid doing it for every init script
# through functions
if [ -f /etc/sysconfig/i18n -a -z "${NOLOCALE:-}" ] ; then
  . /etc/profile.d/lang.sh 2>/dev/null
  export LANGSH_SOURCED=1
fi

# First, run the KILL scripts.
for i in /etc/rc$runlevel.d/K* ; do

        # Check if the subsystem is already up.
        subsys=${i#/etc/rc$runlevel.d/K??}
        [ -f /var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] || continue
        check_runlevel "$i" || continue

        # Bring the subsystem down.
        [ -n "$UPSTART" ] && initctl emit --quiet stopping JOB=$subsys
        $i stop
        [ -n "$UPSTART" ] && initctl emit --quiet stopped JOB=$subsys
done

# Now run the START scripts.
for i in /etc/rc$runlevel.d/S* ; do

        # Check if the subsystem is already up.
        subsys=${i#/etc/rc$runlevel.d/S??}
        [ -f /var/lock/subsys/$subsys ] && continue
        [ -f /var/lock/subsys/$subsys.init ] && continue
        check_runlevel "$i" || continue
                    
        # If we‘re in confirmation mode, get user confirmation
        if [ "$do_confirm" = "yes" ]; then
                confirm $subsys
                rc=$?
                if [ "$rc" = "1" ]; then
                        continue
                elif [ "$rc" = "2" ]; then
                        do_confirm="no"
                fi
        fi

        update_boot_stage "$subsys"
        # Bring the subsystem up.
        [ -n "$UPSTART" ] && initctl emit --quiet starting JOB=$subsys
        if [ "$subsys" = "halt" -o "$subsys" = "reboot" ]; then
                export LC_ALL=C
                exec $i start
        fi
        $i start
        [ -n "$UPSTART" ] && initctl emit --quiet started JOB=$subsys
done
[ "$do_confirm" = "yes" ] && rm -f /var/run/confirm
exit 0
[root@sky ~]#

[root@sky rc5.d]# pwd
/etc/rc5.d
[root@sky rc5.d]# ls
K01smartd        K61nfs-rdma        K89netconsole    S10network         S24nfslock           S55sshd
K02oddjobd       K69rpcsvcgssd      K89rdisc         S11auditd          S24rpcgssd           S70spice-vdagentd
K05wdaemon       K73winbind         K92pppoe-server  S11portreserve     S25blk-availability  S80postfix
K10psacct        K74ntpd            K95firstboot     S12rsyslog         S25cups              S82abrt-ccpp
K10saslauthd     K75ntpdate         K95rdma          S13cpuspeed        S25netfs             S82abrtd
K15htcacheclean  K75quota_nld       K99rngd          S13irqbalance      S26acpid             S90crond
K15httpd         K76ypbind          S01sysstat       S13rpcbind         S26haldaemon         S95atd
K50dnsmasq       K84wpa_supplicant  S02lvm2-monitor  S15mdmonitor       S26udev-post         S99certmonger
K50kdump         K87restorecond     S08ip6tables     S22messagebus      S28autofs            S99local
K60nfs           K88sssd            S08iptables      S23NetworkManager  S50bluetooth
[root@sky rc5.d]#