Shulou(Shulou.com)06/03 Report--

Computer component units: arithmetic unit, controller, memory, output equipment, input equipment five units. (as shown in the figure)

Arithmetic unit: mainly responsible for the calculation and logic judgment of the program

Controller: mainly coordinates the work between peripheral devices and units

Memory: mainly stores data and programs currently being executed

Among them, the combination of arithmetic unit and controller is the central processing unit (CPU). The data read by CPU is obtained from the memory, and the processed data must be stored in the memory first.

CPU internal instruction set, CPU instruction set classification is divided into: reduced instruction set system and complex instruction set system

Reduced Instruction Set (RISC): Reduced instructions, short execution time, high performance, multiple instructions required for complex tasks.

Complex instruction set (CISC): complex instructions, long execution time, a single instruction can handle more complex tasks.

An operating system (OS) is a set of programs designed primarily to manage all activities of a computer and drive all hardware in the system.

Kernel: Control hardware and provide related functions, provide reasonable computer system resource allocation, provide program management, memory management, file system management and other functions. Linux kernel https://www.kernel.org/

Kernel functions: process management, memory management, file system, network functions, hardware drivers, security mechanisms

System call: Also known as system call, provides an interface between user programs and the kernel.

Shell: Human-computer interaction interface, is a program. Shell can be divided into GUI (graphical interface shell) and CLI (command line shell)

GUI (graphical user interface): Gnome C voice development;KDE C++ development; xface lightweight graphical interface

CUI（command line interface):bash sh csh zsh ksh tcsh

To view the shell currently used by Linux: [root@www ~]# echo $SHELL /bin/bash

See available Linux shells: [root@www ~]# cat /etc/shells

Drivers: The operating system provides an interface for manufacturers to create hardware drivers. To use new hardware, manufacturers must install the appropriate drivers.

Applications: Software developed with reference to the development interfaces provided by the operating system, which allows users to operate to achieve certain computer functions.

History of Linux:

In the early 1960s, MIT developed a "compatible time-sharing system"(CTSS), which provided several terminals connected to a host computer to use the host computer's resources for computing work.

Around 1965, Bell Labs, MIT, and GE launched the Multics project to provide more than 300 terminals online at a time.

In 1969 Ken Thompson wrote a core set of programs in assembly language, along with some core utility programs and a small file system. This is the prototype of Unix.

In 1973, Unix was officially born, and Ritchie and others wrote the first official Unix core in C.

BSD (Berkeley software distribution) is a very important branch of UNIX. Sun Corporation developed its own commercial UNIX version based on the core developed by BSD. FreeBSD, which can be installed on x86 hardware architecture, is a modified version of BSD.

1979 Important System V architecture and copyright announcement. In 1979, AT&T introduced the seventh version of UNIX system V, the most important feature of this version is that it can support x86 architecture personal computer system, that is, system V can be installed and run on personal computers, and in this version, AT&T specifically mentioned the strict restriction of "no source code can be provided to students," resulting in many commercial disputes.

In 1984, Richard Mathew Stallman launched the GNU Project and founded the Free Software Foundation (FSF).

In 1988, the graphical interface XFree86 project was launched, XFree86 being an integrated name for Xwindow system + free + x86. The GUI interface for XFree86 was integrated into Linux when Linux kernel version 1.0 was released in 1994.

In 1991, Linus Torvalds announced a small core program on the BBS, which began the extraordinary journey of Linux.

In 1994, Linux 1.0 kernel was released.

Because Linux was developed and maintained by *** engineers in the early days, it did not take into account the ability of ordinary users, so many commercial companies or non-profit teams integrated the Linux kernel with runnable software, plus their own tools, which allowed users to install/manage Linux systems directly on CD/DVD or over the network. This "fully installable Linux kernel + software +tools" thing is called a Linux distribution.

Basic principles of Linux: 1) composed of single-purpose Mini programs, composed of programs to complete complex tasks 2) everything is a file 3) try to avoid capturing the user interface 4) configuration files saved in plain text format

Linux terminals: physical terminals, virtual terminals, analog terminals

Virtual terminal: generated by mingetty program, terminal switching is performed using ctrl+alt+(F1-F6)

Analog terminal: refers to using SSH (secure shell using tcp port 22) to connect to Linux over the network

To see which terminal it is: [root@www ~]# tty /dev/tty2 (virtual terminal 2)/dev/pts/1 (analog terminal 1)

Linux CLI interface: #--root ;$--normal user

Command Format: Command Option Parameters

Options: Short option-, multiple options can be combined-a -b = -ab

Long option--

Parameters: object of command

su(switch user): User switch

su : run a shell with substitute user and group IDs

su [OPTION]... [-][USER[ARG]...]

-，-l，--login：make the shell a login shell

passwd : update user's authentication tokens

SYNOPSIS - passwd [-k] [-l] [-u[-f]] [-d] [-n mindays] [-x maxdays] [-w warndays] [-i inactivedays] [-s] [--stdin] [username]

Tips:

Quick cursor movement: ctrl + a quick jump to the beginning of the line; ctrl + e quick jump to the end of the line

Delete command line content: ctrl + w to delete the word before the cursor;ctrl + u to delete the cursor to the beginning of the line character; ctrl + k to delete the cursor to the end of the line character

Clear the screen: Ctrl + l ;clear

Cancels unexecuted commands: Ctrl + C

Command completion: double-press Tab

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