Linux Basics and Help

first, the operating systemos:operating System, software program for general purpose

Hardware Drivers

Process Management

Memory management

Network management

Security management

File Management

OS classification:

Server Os:rhel, CentOS, Windows server, AIX

Desktop Os:windows 10,windows 7,mac Os,fedora

Mobile device os:android, IOS, YunOS

II. development of Interface StandardsAbi:application Binary Interface

The ABI describes the underlying interface between the application and the OS, allowing the compiled target code to run without modification in a system that uses a compatible ABI

Api:application Programming Interface

The API defines the interface between the source code and the library, so the same source can be compiled in any system that supports this API

Posix:portable Operating System Interface

A series of API standards defined by EEE on the operating system

POSIX-compatible programs can be compiled and executed on other POSIX operating systems

Run Program format:

Windows:exe,. dll (dynamic link library),. lib

Linux:elf,. So (Shared object),. A

third, programming languageLow-level language

Machine language: 0 and 1

Assembly language: Corresponds to machine one by one, unique hardware-related code, driver development

Intermediate Language: C

System-level applications, drivers

Advanced Language: python,go,java,objective-c,c#,php

Application-level program development

Four server three major operating systemsWindows:linux:gnu/linux unix:1969 Ken Thompson

System:bell Lab

AIX (IBM)

Solaris (SUN)

HP-UX (Hewlett-Packard)

BSD: (BSRG) Berkeley System distribution

NetBSD

Openbsd

Freebsd

v. UnixHistory 1965 before and after Multics

Bell Labs, MIT, General Electric initiated

1969 Unix Embryonic UNICs

Ken Thompson Assembly Language B

1973 formally named Unix

Dennis Ritchie C language

1977 BSD

Berkeley Software Distribution Berkeley University

1979 System v Architecture copyright notice

Hp-unix IBM AIX "Do not provide source code for students" reclaim copyright

1984 Minix Operating system

Andrew S. Tanenbaum Computer Science Department, Amsterdam Free University, Netherlands

vi. origin of LinuxOn the October 5 of 1991, Torvalds a message on the Comp.os.minix News Group, formally announcing his own complete free free kernel birth (freeminix-like kernel sources for 386-at) ——— Freax Unix-like kernel, published under the GPL: www.kernel.org Linux operating system:

Complete UNIX-like operating system

Linux kernel + GNU tools

such as: centos,ubuntu,android

Seven Linux distributionsSlackware:suse Linux Enterprise Server (SLES)

openSUSE Desktop

Debian:ubuntu,mint Redhat:RHEL:RedHat Enterprise Linux

Release a new version every 18 months

CentOS: Rhel-compatible format

Kirin: Winning software

Fedora: Release a new version every 6 months

ArchLinux: Lightweight and simple Gentoo: Extreme performance, no traditional installation program lfs:linux from scratch homemade Linux android:kernel+busybox (toolset) +java virtual Machine

Viii. Open Source AgreementThe world's Open source license, there are probably hundreds of

GPLv2, GPLv3, LGPL (lesser): general Public License copyleft

Apache:apache

Bsd:bsd

Mozilla

Apache

MIT

Nine, command promptCommand prompt: Prompt

[Email protected] ~]#

# Admin $ normal User

Show prompt format

[[Email protected] ~] #echo $PS 1

Modify the prompt format

ps1= "\[\e[1;5;41;33m\][\[email protected]\h \w]\\$\[\e[0m\]"

\e \033 \u Current User

\h hostname for short \h host name

\w Current working directory \w current working directory base name

\ t 24-hour time format \ t 12-hour time format

\! Command history number \# command history after boot

10. Execution of ordersEnter command and return

Draw the shell program to find the executable program or code corresponding to the typed command and parse it and submit it to the kernel to allocate resources to run it.

Commands that can be executed in the shell have two types of internal commands: The shell comes with it and is provided by a command

Help Internal Commands list

Enable CMD enables internal commands

Enable–n cmd Disable internal commands

Enable–n View all the disabled internal commands

External command: A corresponding executable program file under the file system path

View path: Which-a |--skip-alias; Whereis

The difference between the specified command is an internal or external command

Type COMMAND

11. Simple commandShutdown: Halt, Poweroff, init 0 restart: reboot, init 6

-F: Force, do not call shutdown

-P: Power off

Shutdown or restart: shutdown

shutdown [OPTION] ... Time [MESSAGE]

-r:reboot

-h:halt

-c:cancel

Time: No designation, default equivalent to +1

Now: Immediately, equivalent to +0

+m: Relative time notation, after a few minutes; for example, +3

HH:MM: Absolute time indication, specify time

User login Information View command:

WHOAMI: Displays the currently logged in active user

Who: All current logon sessions for the system

W: All current logon sessions and actions made by the system

echo Command function: Display character syntax: echo [-nee][string] Description: Echo will send the input string to standard output. The output strings are separated by white space characters, and the line break number option is added at the end:

-E (default) does not support \ Interpret feature

-N Not wrap line

-e enable \ character interpretation function

U Display variables

echo "$VAR _name" variable is replaced with weak reference

Echo ' $VAR _name ' variable does not replace, strong reference

Command replacement: $ () or '

To print the output of one command to the parameters of another command

echo "This system ' s name is $ (hostname)"

This system ' s name is server1.example.com

echo "I am ' whoami '"

I am root

Bracket extension: {}

Print a simplified form of a repeating string

Echo file{1,3,5}

File1 File3 File5

Rm-f file{1,3,5}

echo {1..10}

echo {A.. Z

echo {000..20..2}

12. Tab keyCommand completion

Internal command:

External command: Bash searches for a file named after a given command name from the left and right, based on the path defined by the PATH environment variable, the command to be executed the first time it is found

The user-given string has only one unique command, which complements the entire

Otherwise, tab again will give the list

Path completion

Takes the user-given string as the beginning of the path and searches for the file name at the beginning of the specified string, under its specified ancestor directory

If only: the direct complement

Otherwise: tab to the list again

13. Command Line HistorySave the command history you entered. You can use it to repeatedly execute commands when you log in to the shell, the commands that are recorded in the command history file are read ~/.bash_history the newly executed commands are only recorded in the cache after they are logged in to the shell, and these commands repeat the previous command when the user exits "append" to the command history file , there are 4 ways to repeat the previous command using the UP ARROW keys, and enter to perform the press!!  and enter to execute input!-1 and enter to perform press ctrl+p and enter to execute!:0 Executes the previous command (remove parameter)!n executes the history command output corresponding to the ordinal N of the command!-n to perform the last nth command of the historical record using the up and down keys to navigate up and down the previously entered command C Trl-r to search for commands in command history (Reverse-i-search) ": Ctrl+g: Exit from historical search mode to recall the last parameter in the previous command:!$ represents ESC. (After you click the ESC key Release, and then tap. Key) Alt +. (Hold down the ALT key while you click.) Key) History [-c] [-D offset] [n] history-anrw [filename] history-ps arg [arg ...]

-C: Empty command history

-D Offset: Delete the specified offset command in history

N: Show the recent n history

-a:append, append the newly executed command history list to the history file for this session

-r: Read history file attached to History list

-W: Save History list to specified history file

-N: Read unread rows to History list in history file

-P: Expands the history parameter into multiple lines, but does not exist in the history list

-S: Expands the history parameter into a row, appended to the history list

、

14. Command HelpInternal command: Help command

Mans Bash

External commands: (1) Command--help

Command-h

(2) User manual (manual)

Mans COMMAND

(3) Information page

Info COMMAND

(4) Help documentation for the program itself

Readme

INSTALL

ChangeLog

(5) Official program document

Official site: Documentation

(6) Official documents of the release version

(7) Google

--help OptionsDisplays the usage summary and most of the parameter lists used, but not all of the examples:

Date--help

usage:date [OPTION] ... [+format] or:date [-u|--utc|--universal] [MMDDHHMM[[CC]YY][.SS]]

[] indicates an option

Caps or <> indicates changes in data

... Represents a list

X |y| Z means "x or Y or z"

-abc means-a-b–c.

{} means grouping

Man commandThe File manual page that provides command help is stored in/usr/share/man almost every command has a man's "page" of the man page grouped into different "chapters", collectively known as the Linux Manual Man command configuration file:/etc/man.co Nfig | Man_db.conf

Manpath/path/to/somewhere: Indicates the man file search location

Man-m/path/to/somewhere Command: Search the command command's hand album to the specified location and display the Chinese man needs to install the package MAN-PAGES-ZH-CN Man help paragraph descriptionThe paragraph description in the Help manual:

• Name and brief description
• Synopsis Usage Format Description
• [] Optional content
• <> Required Content
• A|b two Choose one
• {} grouping
• ... The same content can appear multiple times
• DESCRIPTION Detailed description
• Options description
• EXAMPLES Example
• Files Related Documents
• AUTHOR author
• COPYRIGHT Version Information
• REPORTING BUGS Bug Information
• See ALSO other Help references

Man helpView Man manual page

Man [Chapter] keyword

List all Help

Man–a keyword

Search Man Manual

man-k keyword list all matching pages

Using the Whatis database

Equivalent to Whatis

man–f keyword

Print the path to the man Help file

man–w [Chapter] Keyword

Man commandHow to: Use the less command to implement the man command

Space, ^v, ^f, ^f: Flip the screen to the end of the file

B, ^b: Flip the screen to the file header

D, ^d: Turn half screen at the end of the file

U, ^u: Turn half screen to file header

RETURN, ^n, E, ^e or J or ^j: Flip a line to the end of the file Y or ^y or ^p or K or ^k: Flip a line to the file header

Q: Exit

#: Jump To Line #

1 g: Back to File header

G: Turn to the tail of the file

Man Search/keyword:

Searches the end of the file from the current position with the string specified by keyword as the keyword;

N: Next

N: Previous

? KEYWORD:

The string specified by keyword is the keyword, and the file header is searched from the current position;

N: Same direction as search command, next

N: Follow the search command in the opposite direction, previous

Linux Basics and Help