Lesson-2 Yum/single user/rescue mode/linux Boot

Course Outline:
1. Yum uses
Yum is a tool for installing software packages online that can help us solve the dependencies of our packages, which will be described in detail later. We have introduced the following usage: Yum list This command can list all installed and not installed packages
Yum grouplist This command to list all installed and not installed packages
Yum groupinstall-y "Desktop"; Yum groupinstall-y "X window System" We used this command to install a graphical desktop
Init 5 or STARTX allows us to switch to the graph
Yum update automatically upgrades to latest version 6.6

Yum Groupinstall-y "ChineseSupport "Install Chinese supported

2. Single User
Restart linux,3 seconds, press ENTER.
If you have a grub password, you need to press P first, enter the password before you can do the following
Press E, select the second row, and then press E
Add single or number 1 or letter s on the last side
Press ENTER first and then press B
This will successfully enter single-user mode, we can change the root password

3. Rescue mode
If the real machine, need to have a CD-ROM or a USB flash drive, restart into the BIOS to tune into the CD-ROM boot, select ' Rescue installed system '
Language we default, keyboard type also default
Rescue Method also remains the default
Whether to enable the network when using rescue mode, according to the actual situation, here Amin Select No (using the TAB key)
Three modes can choose: Shell mode will go directly to the command line, can be done to edit files, modify user password, etc. fakd is the diagnostic mode; reboot will restart directly; Select the first shell mode
Execute a command: chroot/mnt/sysimage

4. Operating level
Linux has 7 operating levels: 0-6
0: Turn off the machine
1: Single User
2: Level 3 without NFS service
3: Command-line mode, that is, no graphics service
4: Reserved
5: Graphical mode
6: Restart
Then we can use the command init + runlevel number to switch between modes, for example, after we have installed the graphical interface, in command line mode, the input command init 5 can be entered into the graphical interface. In the graphical interface, open the terminal software, input command init 3 can enter the command line mode. Similarly, we input the init 0 can be shutdown, input init 6 can be restarted

5. Linux boot process
BIOS power-on self-test, find the boot media to locate the MBR
After the MBR is found, the location of the kernel is located according to the bootloader (grub) settings
Execute Linux kernel image code to detect and load hardware drivers
After the driver loading is complete, the kernel gives the initiative to Init
Init will initialize the system according to the operating level set by the system.
/etc/init/rcs.conf
Exec/etc/rc.d/rc.sysinit, activating swap partitions, checking disks, loading hardware modules, and other tasks that require priority execution
EXEC/ETC/RC.D/RC $RUNLEVEL ($RUNLEVEL = = 3)
/etc/rc.d/rc3.d/
/etc/rc.d/rc.local
Set up a terminal: 6 TTY and 1 graphics
User Login

Preview information ...
Rescue mode: http://user.qzone.qq.com/521279508?ptlang=2052
Run Level inittab:http://www.cnblogs.com/linuxsuda/p/4249650.html
Linux Boot: http://blog.chinaunix.net/uid-23036581-id-2230525.html

Lesson-2 Yum/single user/rescue mode/linux Boot