Linux 5 guiding process 1

Linux boot process course outline "#1 Linux boot process #2 Linux running level #3 Linux Startup Service Management #4 grub configuration and application #5 startup Fault Analysis and Resolution" System Boot Process 『 firmware firmware (CMOS/BIOS) → post power-on self-check period [the section where CMOS is fixed on the motherboard Program The BIOS operating CMOS interface] bootloader (grub) → load the kernel Linux-grub/etc/grub. conf/win-ntldr [NT kernel code, loader] bootini [Recording startup information] kernel loading kernel, OS core-kernel [storing CPU file process... management]-The heart brain specifies the location where the Linux kernel is stored. Ls/Boot Load kernel → driver hardware kernel [the kernel only does two things, 1 driver Hardware 2 start init. the driver stores the most in the kernel] the startup process init ready [init is the first process that can exist and start] reads the execution configuration file/etc/inittab ---------------- description 1: After firmware self-check, after finding that there are no problems with the hardware, firmware then reads the MBR [Master Boot Record], located in the 0-cylinder, 0-head, 1-sector, and jumps to the Master Boot Record to read data. A very important piece of data in the MBR is called bootloader, which is also called a self-lifting program or self-starting program. below is the Partition Table of the partition table on the disk. below is the description of the magic number ending symbol 2: the Linux kernel is Source code File. After unpacking, a bunch of sources are found.Code File, Linux does not have a compiled kernel. You can compile and upgrade the kernel by yourself. NOTE 3: After init is started, read the inittab file and execute the default running level to continue the boot process. In Unix systems, init is the first process that can exist. Its PID is always 1, but it must also be responsible for a more advanced function: the kernel scheduler (kernelscheduler) with a PID of 0 to obtain the CPU time. Extension: in Linux, orphan processes are not allowed. In Linux, init is the parent process of all processes. The zombie process [Z] is dead, and the father does not know that this sub-process will become Z. NOTE 4: The apache service file. conf is abbreviated as config. Some are called ~ The abbreviation of tab. Table. Inittab [not in Ubuntu, but it seems that you can create one by yourself!] Windows press F8, similar to runlevel [A service developed by Sun in 2, 3 NFS Network File System, which can achieve file sharing between UNIX and Unix. It is not good for UDP ..] 0 shutdown 1 Character single user 2 or 3 character interface multi-user mode [widely used server mode] 4 custom 5 graphical Multi User 6 reboot "common firmware Settings" Security Settings bootable media list wizard media search sequence power management startup detail display ...... "firmware has a hardware clock. OS has a Software Clock to be regularly synchronized. #1 How to synchronize data in Linux # date # hwclock -- help option hctosys systohc if both of them are incorrect, so the -- set option can set your hardware clock, and the software is the same.