CentOSLInux启动关闭服务管理.docx

CentOS LInux启动关闭和服务管理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）。2.经BOIS的控制，将MBR中的Boot Record调入内存中。这里就要说说Linux的Boot程序了，Linux的Boot程序有GRUB和LILO，而CentOS默认的Boot程序是ＧＲＵＢ。3.通过Boot程序，访问硬盘中的Linux内核程序。4.将内核程序调入内存中。5.内核程序调用完成后，通过内核访问硬盘中将要用到的其他文件。内核第一个执行的文件是/sbin/init，而这个文件的设置和定义文件是/etc/inittab这个文件，也就是说/sbin/init按照/etc/inittab的定义来执行下一步的启动，那我们就要看看/etc/inittab文件是怎么回事儿了。[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@ 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 mode12?? # 2 - Multiuser, without NFS (The same as 3, if you do not have networking)13?? # 3 - Full multiuser mode14?? # 4 - unused15?? # 5 - X1116?? # 6 - reboot (Do NOT set initdefault to this)17?? #?18?? id:3:initdefault: ← 默认的启动模式19??20?? # System initialization.21si::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 125?? l2:2:wait:/etc/rc.d/rc 226?? l3:3:wait:/etc/rc.d/rc 327?? l4:4:wait:/etc/rc.d/rc 428?? l5:5:wait:/etc/rc.d/rc 529?? l6:6:wait:/etc/rc.d/rc 630??31?? # Trap CTRL-ALT-DELETE32?? 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 minutes35?? # of power left.?? Schedule a shutdown for 2 minutes from now.36?? # This does, of course, assume you have powerd installed and your37?? # 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 Powe