Basic Linux configuration and management ---

Linux basic configuration and management-Linux system startup explanation 1 system startup process BIOS-& gt; MBR + bootcode-& gt; run the pilot program: GRUB-& gt; load the kernel-& gt; execute init-& gt; run runlevel2 to start detailed explanation 1BIOS1BIOS... linux basic configuration and management-Linux system startup details 1 system startup process BIOS-> MBR + boot code-> run the boot program: GRUB-> load the kernel-> execute init-> run runlevel 2 start details 1 BIOS 1 BIOS refers to the basic input output system (basic input output system ), generally, in the BIOS chip stored on the motherboard, the first step for 2 computers to start is to start the BIOS first, then the BIOS checks the hardware and finds the device that can be started. 3 The device can be set in the BIOS, including USB, CDROM, and HD. 2 MBR 1 MBR is 512 bytes, the first 446 bytes is the boot code 2 BIOS. "The last two bytes in the 512 bytes of the first sector are 55aa to determine that" the device is the boot device 3 MBR is just to load the boot program GURB 3 GRUB 1 GRUB is currently the mainstream boot program for Linux. 2 GRUB can guide almost all of the operating systems. 3 GRUB-related files are stored in/boot/grub. 4 KERNEL 1 MBR boot code will be responsible find and load the Linux kernel 2 and save it in/boot/vmlinuz ...... 3. the package file/boot/init of the kernel module is also loaded ..... 4 Linux will compile some uncommon drivers into modules in order to keep the kernel simple, and then dynamically load them when necessary, these modules are saved as initrmfs files 5 early Linux uses initrd files, but most of the current Linux versions use initrmfs, which can save more space, more flexible 6 command dmesg can be used to view the output information of the kernel to be started 5 INIT 1 init is the first process running in Linux, init is the parent process of all processes, 1 2 call/etc/rc. d/rc. sysinit to initialize the system and mount the file system, and start the corresponding program based on the running level. 3. Linux running level: 0. Shutdown. 1. single-user mode. 2. multi-user mode without network; 3. multi-user mode with command line; 4. 5 graphical interfaces; 6. restart 4 we can view the previous and current running level through runlevel 5 command init can be used to view and change the current running level 6 single user change root password 1 to pass the parameter "1" or" single "enables the system to enter single-user mode 2 single-user mode without starting any services 3 single-user mode directly log on as root, password 4 is not required. we can use passwd to change the root password. 5 because anyone close to our physical machine may change our root password, therefore, we can use GRUB encryption to prevent the password from being changed. add a line of password in the startup settings in conf -- md5 encrypted string password we can generate through the grub-md5-crypt