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CentOS LInux启动关闭和服务管理（zt）
CentOS启动顺序： 1.当我们按下电源按钮，把电源投入到机器中后，首先被启动执行的就是这个BIOS（BasicInput/Output System）程序。BIOS的功能是......并且访问硬盘先头512Bit的MBR（Master Boot Record）。 [root@linux ~]# cat -n /etc/inittab
1 # 2 # inittab This file describes how the INIT process should set up 3 # the system in a certain run-level. 4 # 5 # Author: Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org> 6 # Modified for RHS Linux by Marc Ewing and Donnie Barnes 7 # 8 9 # Default runlevel. The runlevels used by RHS are: 10 # 0 - halt (Do NOT set initdefault to this) 11 # 1 - Single user mode 12 # 2 - Multiuser, without NFS (The same as 3, if you do not have networking) 13 # 3 - Full multiuser mode 14 # 4 - unused 15 # 5 - X11 16 # 6 - reboot (Do NOT set initdefault to this) 17 # 18 id:3:initdefault: ← 默认的启动模式 19 20 # System initialization. 21 si::sysinit:/etc/rc.d/rc.sysinit ← boot时的处理 22 23 l0:0:wait:/etc/rc.d/rc 0 ← 23-29行，各启动模式的处理，分别启动/etc/rc.d/rcX.d脚本 24 l1:1:wait:/etc/rc.d/rc 1 25 l2:2:wait:/etc/rc.d/rc 2 26 l3:3:wait:/etc/rc.d/rc 3 27 l4:4:wait:/etc/rc.d/rc 4 28 l5:5:wait:/etc/rc.d/rc 5 29 l6:6:wait:/etc/rc.d/rc 6 30 31 # Trap CTRL-ALT-DELETE 32 ca::ctrlaltdel:/sbin/shutdown -t3 -r now ← Ctrl+Alt+Del被激活时的处理 33 34 # When our UPS tells us power has failed, assume we have a few minutes 35 # of power left. Schedule a shutdown for 2 minutes from now. 36 # This does, of course, assume you have powerd installed and your 37 # UPS connected and working correctly. 38 pf::powerfail:/sbin/shutdown -f -h +2 "Power Failure; System Shutting Down" ← 电源off时的处理 39 40 # If power was restored before the shutdown kicked in, cancel it. 41 pr:12345:powerokwait:/sbin/shutdown -c "Power Restored; Shutdown Cancelled" ← 电源on时的处理 42 43 44 # Run gettys in standard runlevels ← 45-50行是6个虚拟终端 45 1:2345:respawn:/sbin/mingetty tty1 46 2:2345:respawn:/sbin/mingetty tty2 47 3:2345:respawn:/sbin/mingetty tty3 48 4:2345:respawn:/sbin/mingetty tty4 49 5:2345:respawn:/sbin/mingetty tty5 50 6:2345:respawn:/sbin/mingetty tty6 51 52 # Run xdm in runlevel 5 53 x:5:respawn:/etc/X11/prefdm -nodaemon ← 启动模式5的时候，启动/etc/X11窗口系统 [root@linux ~]#
这里18行定义的是启动级别3，就执行26行中启动级别3的定义，执行/etc/rc.d/rc脚本文件（控制文件），并将18行定义的启动级别以参数的形势交给/etc/rc.d/rc文件进行处理。这里我们看到“l3:3:wait:/etc/rc.d/rc 3”是把启动级别3交给文件rc处理，那我们有必要看看rc文件都定义了什么。 [root@linux ~]# cat -n /etc/rc.d/rc
1 #! /bin/bash 2 # 3 # rc This file is responsible for starting/stopping 4 # services when the runlevel changes. 5 # 6 # Original Author: 7 # Miquel van Smoorenburg, <miquels@drinkel.nl.mugnet.org> 8 # 9 10 # check a file to be a correct runlevel script 11 check_runlevel () 12 { 13 # Check if the file exists at all. 14 [ -x "$1" ] || return 1 15 16 # Reject backup files and files generated by rpm. 17 case "$1" in 18 *.rpmsave|*.rpmorig|*.rpmnew|*~|*.orig) 19 return 1 20 ;; 21 esac 22 return 0 23 } 24 25 # Now find out what the current and what the previous runlevel are. 26 argv1="$1" 27 set `/sbin/runlevel` 28 runlevel=$2 29 previous=$1 30 export runlevel previous 31 32 . /etc/init.d/functions 33 34 # See if we want to be in user confirmation mode 35 if [ "$previous" = "N" ]; then 36 if [ -f /var/run/confirm ]; then 37 echo $"Entering interactive startup" 38 else 39 echo $"Entering non-interactive startup" 40 fi 41 fi 42 43 # Get first argument. Set new runlevel to this argument. 44 [ -n "$argv1" ] && runlevel="$argv1" 45 46 # Is there an rc directory for this new runlevel? 47 [ -d /etc/rc$runlevel.d ] || exit 0 48 49 # First, run the KILL scripts. 50 for i in /etc/rc$runlevel.d/K* ; do 51 check_runlevel "$i" || continue 52 53 # Check if the subsystem is already up. 54 subsys=${i#/etc/rc$runlevel.d/K??} 55 [ -f /var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] \ 56 || continue 57 58 # Bring the subsystem down. 59 if egrep -q "(killproc |action )" $i ; then 60 $i stop 61 else 62 action $"Stopping $subsys: " $i stop 63 fi 64 done 65 66 # Now run the START scripts. 67 for i in /etc/rc$runlevel.d/S* ; do 68 check_runlevel "$i" || continue 69 70 # Check if the subsystem is already up. 71 subsys=${i#/etc/rc$runlevel.d/S??} 72 [ -f /var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] \ 73 && continue 74 75 # If we're in confirmation mode, get user confirmation 76 if [ -f /var/run/confirm ]; then 77 confirm $subsys 78 test $? = 1 && continue 79 fi 80 81 update_boot_stage "$subsys" 82 # Bring the subsystem up. 83 if [ "$subsys" = "halt" -o "$subsys" = "reboot" ]; then 84 export LC_ALL=C 85 exec $i start 86 fi 87 if egrep -q "(daemon |action |success |failure )" $i 2>/dev/null \ 88 || [ "$subsys" = "single" -o "$subsys" = "local" ]; then 89 $i start 90 else 91 action $"Starting $subsys: " $i start 92 fi 93 done 94 rm -f /var/run/confirm 95 if [ -x /usr/bin/rhgb-client ] && /usr/bin/rhgb-client --ping ; then 96 /usr/bin/rhgb-client --quit 97 fi [root@linux ~]# 在这个文件中我们看看如下的几行：
在这个文件中，每个程序块的部分都有注释（#开头的行），如果有兴趣的话可以自行研究一下。似乎不是那么太难，就是check→do，确认后执行，判断后执行的样子。 [root@linux ~]# ls -l /etc/rc.d
总用量 112 drwxr-xr-x 2 root root 4096 12月 28 12:45 init.d -rwxr-xr-x 1 root root 2352 2004-03-17 rc drwxr-xr-x 2 root root 4096 12月 28 12:45 rc0.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc1.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc2.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc3.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc4.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc5.d drwxr-xr-x 2 root root 4096 12月 28 12:45 rc6.d -rwxr-xr-x 1 root root 220 2003-06-24 rc.local -rwxr-xr-x 1 root root 27584 8月 13 17:10 rc.sysinit [root@linux ~]# 我们看到了，在这个目录下面，有刚才提到的rc文件，还有另外的一些文件，我们来简单说明一下。 [root@linux ~]# ls -l /etc/rc.d/rc3.d
合計 224 lrwxrwxrwx 1 root root 21 1月 5 05:24 K01tog-pegasus -> ../init.d/tog-pegasus lrwxrwxrwx 1 root root 13 1月 5 05:12 K01yum -> ../init.d/yum lrwxrwxrwx 1 root root 24 1月 5 05:12 K02NetworkManager -> ../init.d/NetworkManager lrwxrwxrwx 1 root root 15 1月 5 05:12 K03rhnsd -> ../init.d/rhnsd lrwxrwxrwx 1 root root 19 1月 5 05:08 K05saslauthd -> ../init.d/saslauthd lrwxrwxrwx 1 root root 16 1月 5 05:11 K10psacct -> ../init.d/psacct lrwxrwxrwx 1 root root 17 1月 5 05:25 K12FreeWnn -> ../init.d/FreeWnn lrwxrwxrwx 1 root root 13 1月 5 05:12 K20nfs -> ../init.d/nfs lrwxrwxrwx 1 root root 14 1月 5 05:11 K24irda -> ../init.d/irda lrwxrwxrwx 1 root root 16 1月 5 05:10 K50ibmasm -> ../init.d/ibmasm lrwxrwxrwx 1 root root 17 1月 5 05:12 K50netdump -> ../init.d/netdump lrwxrwxrwx 1 root root 16 1月 5 05:26 K73ypbind -> ../init.d/ypbind [root@linux ~]# 接下来我们看看控制服务的一些工具 from：http://www.centospub.com/bbs/viewthread.php?tid=1295&highlight= --End-- |
