系统的初始化

5. 关闭系统及重启系统（详见linux系统管理P342）
1) 掌握常用的可以关闭系统的命令：
shutdown -h now 
halt
poweroff
init 0

2) 掌握常用的可以重启系统的命令：
shutdown -r now
reboot
init 6
Ctrl+Alt+Delete键

6. 掌握单用户模式修改用户的密码

#进单用户模式
按任意键----e---->选择第二行 kernel ---->按e, 再按空格 >输入1----再输入b

#查看运行级别
runlevel 
1 $

#修改密码
passwd root

#再重新启动

reboot

7. 掌握救援模式

1、插入光驱ISO
2、开机快速按F2---设光驱启动
3、重启服务器

4、用户光盘启动系统，并选择rescue installed system

5、启动后会让设置一些列相关设置：

语言设置：

键盘设置：

 

是否启用网卡，可以启用，我选不启用：

一说说明，点continue：

提示将要将之前的系统挂载到/mnt/sysimage,点ok进行下一步：

已经将之前的系统挂 载到/mnt/sysimage，点ok：

选择shell start shell，点ok即可进入到linux救援模式：

 

修改grub.conf，将之前的grub保护密码删除或注销

 

重启系统使用单用户模式重新设置root密码：

再此仍然可以将密码重新设置。

8. 课后作业（用时70分钟）
1) 以root用户登录系统

2) 修改grub配置文件，默认以第1个操作系统启动，将默认的读秒修改为10秒

[root@study ~]# vi /etc/grub.conf

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/sda3
# initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=10
splashimage=(hd0,0)/grub/splash.xpm.gz
#boot=/dev/sda
default=0
timeout=5 #系统进入系统的时间
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
password --encrypted $6$bwpMzA6qyot6Fem4$F1bD/iZa2rHHQKnnicET4kTKvYbSYZLBdu4gG1N6oHJtLPgxbJsACtPR3wqetr.4zBDRfPKESWGFgv8sNsf5i1
title CentOS 6 (2.6.32-504.el6.x86_64)
root (hd0,0)
@ 
"/etc/grub.conf" 18L, 930C written

3) 设置grub菜单密文密码“123”

[root@study ~]# grub-md5-crypt
Password: 
Retype password: 
$1$D/gW2/$aFrbVkK8itwGxpg3UEqwg1

[root@study ~]# vi /etc/grub.conf

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/sda3
# initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5 #系统进入系统的时间
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
password --$1$D/gW2/$aFrbVkK8itwGxpg3UEqwg1    #设置密码
password --encrypted $6$bwpMzA6qyot6Fem4$F1bD/iZa2rHHQKnnicET4kTKvYbSYZLBdu4gG1N6oHJtLPgxbJsACtPR3wqetr.4zBDRfPKESWGFgv8sNsf5i1
title CentOS 6 (2.6.32-504.el6.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-504.el6.x86_64 ro root=UUID=db12d77f-2b16-4a49-b848-3200e873fecd rd_NO_LUKS rd_NO_LVM LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet
initrd /initramfs-2.6.32-504.el6.x86_64.img

4) 修改系统的默认运行级别为3

[root@study ~]# vi /etc/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:3:initdefault:   #红色部分修改成：3
~

5) 使用与运行级别有关的命令重启系统

reboot or init 6 

6) 使用单用户模式修改用户的密码为“123”

7) 使用救援模式删除grub菜单密码