阅读以下说明，回答问题1至问题8。 [说明] Linux 系统开机引导时首先启动内核，由内核检查和初始化硬件设备，载入设备的驱动程序模块，安装root文件系统，然后内核将启动一个名为init的进程。在init运行完成并启动其他必要的后续进程后，系统开始运行，引导过程结束。init进程启动时需要读取inittab配置文件，该文件确定init在系统启动和关机时的工作特性。典型的inittab文件内容见以下清单： inittab This file describes how the INIT process should set up the system in a certain nm-level. Default nmlevel. The nmlevels used by RHS 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-Xll 6 - reboot (Do NOT set initdefault to this ) id:5:initdefault: System initialization. si::sysinit:/etc/rc.d/rc.sysinit 10:0:wait:/etc/rc.d/rc 0 11:1:wait:/ete/rc.d/rc 1 12:2:wait:/etc/rc.d/rc 2 13:3:wait:/etc/rc,d/rc 3 14:4:wait:/etc/rc.d/rc 4 15:5:wait:/etc/rc.d/rc 5 16:6:wait:/etc/rc.d/rc 6 Trap CTRL-ALT-DELETE ea::ctrlaltdel:/sbin/shutdown -t3 -r now When our UPS tells us power has failed, assume we have a few minutes of power left. Schedule a shutdown for 2 minutes from now. This does, of course, assume you have powerd installed and your UPS connected and working correctly. pf::power fail:/sbin/shutdown -f-h +2 'Power Failure: System Shutting Down' If power was restored before the shutdown kicked in, cancel it. pr: 12345:powerokwait:/sbin/shutdown-c 'Power Restored; Shutdown Cancelled' Run gettys in standard rtmlevels 1:2345 :respawn:/sbin/mingetty tty1 2:2345:respawn:/sbin/mingetty try2 3:2345 :respawn:/sbin/mingetty try3 4:2345:respawn:/sbin/mingetty tty4 5:2345:respawn:/sbin/mingetty tty5 6:2345 :respawn:/sbin/mingetty tty6 Run xdm in runlevel 5 x:5:respawn:/etc/X 11/prefdm -nodaemon 启动init进程前，不需要经过______步骤。