Lesson 21:linux System Start-up detailed
- Bios->mbr:boot code-> Execute bootloader-grub-> load kernel--Execute Init->runlevel
- BIOS (Basic Input Output System), generally saved in the motherboard of the BIOS chip, the computer starts, the first run, the BIOS is responsible for checking and find the bootable settings, bootable device in the BIOS settings, such as Usb,cdrom,hd
- Mbr,bios after locating the bootable device and executing its boot code, the boot code is the first 446 bytes of the MBR
- Grub, now used by Linux mainstream boot program, can almost boot all operating systems, grub configuration file in the/boot/grub/directory, stage1 size of 512 bytes, the actual MBR image.
- KERNEL,MBR's boot code will be responsible for locating and loading the Linux kernel, and the Linux kernel is saved in/boot/vmlinuz-2.6.32-279.el6.i686. Command DMESG to view the output of the kernel at this boot
- Init,init is the first process running in a Linux system, calling/etc/rc.d/ Rc.sysinit is responsible for initializing the system, mounting the file system, and starting the corresponding service according to the RunLevel, Linux runlevel, 0-shutdown, 1-single-user mode, 2-multiuser mode without network, 3-multiuser mode, 4-unused, 5-xii graphical mode; 6-restart
- The default operating level can be configured by/etc/inittab, and other basic in the/etc/init/directory, including Ctrl+alt+del. Command init+ number, you can toggle the current run level, runlevel, you can view the previous and current RunLevel
- Single-User change root password, pass parameter 1 or single for the kernel, no task service is started by user mode, log in directly with root user, and do not need secret. Temporarily grub on startup, passing parameter 1 to the kernel to enter single-user mode. PASSWD, you can change the password without the need for an old password.
- Grub encryption encrypts grub by adding the following parameters to the boot configuration in/boot/grub/grub.conf: Password--md5 MD5 string. Grub-md5-crypt, you can md5 a cipher string.
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Lesson 22:linux Software Management
- Source code form, the vast majority of open source software is directly published in the form of source code, will generally be packaged into tar.gz archive compressed files, the source code basic compilation process: 1-./configure: Check the compilation environment, related library files, and configuration parameters and generate makefile;2- Make: Compile the source code to generate the executable file; 3-make install installs the resulting executable file to the current computer
- RPM (Redhat Package Manager) simplifies the installation management of open source software by compiling source code into executables based on a specific platform system and saving dependencies. RPM Design Catalog: Use simple, single package format file publishing (. rmp file), upgradeable, tracking software dependencies, basic information queries, software validation features, payment multiplatform.
- RPM Basic command: Install software: rpm-i software.rpm; Uninstall software: Rpm–e software.rpm; Upgrade: Rpm–u software.rpm; Install via HTTP,FTP protocol: RPM–IVH http://xxx/ xxx/xxx.rpm
- RPM Query
- RPM Verification
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Lesson 23:yum
- YUM (Yellowdog Updater Modified) is a RPM front-end program designed to automatically solve RPM-dependent rpm dependency issues. Features: Automatically resolve dependencies, can group RPM, and group-based installation, the introduction of warehouse concepts, support multiple warehouses, simple configuration
- The repository configuration file is saved in the/etc/yum.repos.d/directory in the following format:
- Yum Basic command: Yum install xxx;yum remove xxx;yum update xxx
- Yum query: Yum search Keyword;yum list (all|installed|recent|updates); Yum info packagename;yum whatprovides filename Which package does the query file belong to?
- Create a Yum repository
- Yum cache: After the configuration of the Yum repository is modified, the cache can be cleaned up by Yum clean.
Linux Introductory Learning (ix)
