14th Linux Startup Management (2) _ Boot loader grub

2. Boot boot program Grub

2.1 Grub configuration file

(1) Representation of partitions in grub

Hard disk	Partition	Linux Device file name	Device file name in Grub
Block 1th SCSI HDD	1th Primary Partition	/dev/sda1	HD (0,0)
	2nd Primary Partition	/dev/sda2	HD (0,1)
	Extended partition	/dev/sda3	HD (0,2)
	1th logical Partition	/dev/sda5	HD (0,4)
Block 2nd SCSI HDD	1th Primary Partition	/dev/sdb1	HD (1,0)
	2nd Primary Partition	/dev/sdb2	HD (+)
	Extended partition	/dev/sdb3	HD (+)
	1th logical Partition	/dev/sdb5	HD (1,4)

(2) Grub configuration file: #vi/boot/grub/grub.conf

　①default=0 boot 1th System by default

②timeout=5 wait time, default is 5 seconds

③splashimage= (hd0,0)/grub/splash.xpm.gz here specifies where to save the background image file when Grub starts (typically under/boot/grub/)

④hiddenmenu hidden Menu

⑤title CentOS (2.6.32-642.el6.i686) title

⑥root (hd0,0) refers to the save partition of the startup program

⑦kernel/vmlinuz-2.6.32-642.el6.i686 ro root=uuid=71c20ba0-4900-4

3cf-a18b-21f5ef11b893 Rd_no_luks keyboardtype=pc keytable=us rd_no_

MD Crashkernel=auto LANG=ZH_CN. UTF-8 RD_NO_LVM rd_no_dm RHGB quiet

Defining options for Kernel nucleation

⑧INITRD/INITRAMFS-2.6.32-642.EL6.I686.IMG specifies where the Initramfs memory file system image file is located.

2.2 Grub adjustment of encryption and character interface resolution

(1) Grub encryption

① startup, when the countdown to select "Operating System" appears , press any key to enter the Grub interface

② Press "E key", can directly edit Grup

③ to prevent this unsafe behavior of pressing the "E key" directly into the edit grub file, it can be encrypted.

#grub-md5-crypt//　　　　 generate an encrypted cipher string

Password://Enter the password to be added for grub, such as 123456

Retype password://Enter password again

$1$wbwv7/$SKnbyZ 88.xl7lfyzbza9p. The generated cipher string

　　　　#vi/boot/grub/grub.conf

then save, restart, and press any key to enter the grub interface while waiting for the operating system to be selected　　　　 .

(2) Adjustment of character interface resolution

① query whether the kernel supports resolution adjustment : (To see the effect in the virtual machine!) The remote tool is invalid! ）

　# grep "Config_framebuffer_console"/boot/config-2.6.32-642.el6.i686

Config_framebuffer_console=y//Support adjust resolution

Config_framebuffer_console_detect_primary=y

Config_framebuffer_console_rotation=y

② setting of adjustment parameters

Color depth	640x480	800x600	1024x768	1280x1024
8 Guests	769	771	773	775
15 Guests	784	787	790	793
16 Guests	785	788	791	39°
32 Guests	786	789	792	795

③ Modifying the Grub configuration file and changing the resolution

14th Linux Startup Management (2) _ Boot loader grub