[Linux] explanation of basic operation instructions

brief introduction ：

        Linux The directory structure and file organization form of the operating system are organized in the form of multi fork tree . Why? ？ It's not just Linux , Many mainstream operating systems are multi tree structures .

The advantage of it is ： Easy to find , And all documents have a unique identification method ; Because each child node has only one parent node , So the path from the leaf node to the root node is unique , conversely , The path from the root node to the leaf node is also unique .

Let's introduce the basic instructions ：

ls Instructions ：

1、 A separate ls ： Display the files in the current directory （ file name ）.

2、ls -l ： It can be abbreviated as ：ll ; Show more attribute information , It's like windows Property view of .

3、ls -a ： Show . The first hidden file and normal file .

4、ls /home/xx/test.c  ： View the file through the absolute path .

  Because the path is absolutely unique , So you can enter anywhere , The disadvantage is too much trouble .

5、ls ../xx/ ： View files through relative paths .

  The disadvantage is that the path changes , The current path will fail , Absolute path is recommended .

6、ls -d / ls -d xx ： Show only information about this directory , By default . .

7、ls -n ：  Replace users with numbers .

8、ls -r / ls -R ： Display all files under each directory ,-r Show current directory , -R Displays the subdirectories of each directory under the current directory .

 clear 、pwd、whoami、nano、tree Instructions ：

1、clear ： Clear the screen .

2、pwd ：  Displays the directory where the current path is located ,windows Overhead path

Ordinary users ：/home/xxx It's called a multi person dormitory xxx The user's home working directory , Default path after login ;

root user ：/root It's called a single room dormitory , Is the main working directory of the Administrator .

' / ' be called Linux The path separator for , Keypad 159 ;

 ' \ ' yes windows The delimiter , Keypad 357.

3、whoami ： View the current user .

4、nano ： Notepad tools .

5、tree ： Print each document in a tree structure , You need to configure the environment .

 mkdir、touch Instructions ：

1、touch xxx ： Create files in the current directory , coca xxx.txt 、xxx.c.

2、mkdir xx ： Create directory , Create a directory in the current directory , The path can be added after .

3、mkdir -p xx/xx/xx ： Create directory recursively .

 rm Instructions ：

1、rmdir xx ： Delete directory , Can only be used to delete empty directories .

2、rm -r xx： Recursive delete , file 、 Everything such as non empty directory can be deleted , Delete ordinary files rm xx that will do , When deleting some files that are out of permission or protected, you will be asked to enter Y / N .

3、rm -rf xx ： Mandatory deletion , Popular on the Internet " rm -rf / " Delete the library and run away , This is not recommended .

4、rm * or rm ./ *： Delete all files in the current directory ,' * ' Is a wildcard , Suggest using rm ./ * ,rm -r * Delete directory . 

cd Instructions ：

1、cd xxx ： Entry directory .cd + ls amount to windows Double click the directory in to enter

2、cd .. ： Return to parent directory , In the directory ' . ' Represents the current directory ,' .. ' On behalf of the parent directory .

3、cd - ： Go back to the previous Directory , Repeat the operation to jump back and forth .

 4、cd ~ ： Go to your home directory （ This user ）, ' ~ ' Represents the root directory .

man Instructions ：

1、man ： Command Reference Manual .

2、man 3 xxx ： Check the manual of the corresponding command .

Library function -- 3

command  -- 2

system call -- 1 , No default 1 Manual No .

3、cman ： Chinese version of the manual , You need to configure the environment .

cp Instructions ：

1、cp test.c xx ： Copy files test.c To xx Under the path , windows Medium ctrl c + ctrl v.

2、cp -r ：  replica catalog ,-r It means recursion .

3、cp -rf * ： Copy all files .

4、cp -rf *.txt ： Copy all txt file , You can change to other types .

mv Instructions ：

mv It has the function of cutting and renaming , You can cut the directory without ' -r ' .

1、mv a.txt b.txt ： take a.txt Rename as b.txt.

2、mv test.c xx： Cut the file to xx Under the path .

Other functions and cp The same command .

cat 、tac Instructions ：

1、cat xx.txt ： Show text content .

2、cat -n xx.txt ： Display text with line number .

3、tac ： Flashback display .

more 、less 、head、 tail Instructions ：

1、more xxx ： Look back before .

2、less xxx ： It can be viewed up and down .

3、head xxx ： Default view before 10 That's ok .

4、head -n3 xxx or head -3 xxx ： Adjustable to see how many lines .

5、tail xxx ： After default view 10 That's ok , Usage and head identical .

6、head -1010 xxx | tail -10 ： The line number can be controlled by pipeline .

echo Redirection instructions ：

1、echo '' xxx '' ：  The output content is displayed on the display by default .

2、echo '' xxx ''  > test.txt ： Redirect content output to txt In file , What is redirection ？ It refers to the file that should be output to the display , The results are printed into the file , This is called redirection . Every redirect will empty , To write .

3、>> ： Append redirection , You don't have to empty the contents , Append to the end .

cat And echo The difference between ：cat Followed by the filename , echo Follow the string .

ps： Why can they be output directly to the display , Instead of the header file ,c In the program, the header file must be wrapped before printing .

The reason is that the operating system will open three files by default ：stdin 、stdout 、stderr , stay printf This interface encapsulates fwrite Such as function , So it can output .

date 、cal Instructions ：

date It's a time order ;

1、 A separate date ： Original display .

2、date +%Y / %m / %d --- %H：%M：%S ： Print mm / DD / yyyy , Minutes and seconds , In the middle of the / - ： Can be replaced with any symbol .

3、date +%s ： Check the timestamps , from 1970/01/01--08:00 Start , Because of geographical time difference 8;

4、date -d @ Time stamp ： Display the original time according to the timestamp .

5、cal ： Look at the calendar of the month .

6、cal 2020 ： Check the calendar of the current year .

7、cal -3 ： See the former 、 in 、 One month later .

find 、which 、 whereis  Instructions ：

1、find xxx -name aa ： stay xxx Under the path, search by name with aa The file of .

2、find xxx -size 1000 ： find xxx The size under the path is 1000 The file of , You can add -size 1010 , Point to 1000 - 1010 Size range .

3、find xxx type d ： stay xxx Find... In the path d Properties file .

4、which + command ： The command to find the command .

5、whereis + command ： Find all with ls Information about .

grep Instructions ：

grep It's a line filter tool .

1、grep ' hello ' test.txt ： stay test.txt View all files with 'hello' The line of .

2、grep -n ... ： The basis above is to display the line number .

3、grep +v ： Inversely select the information content .

4、grep -i ' xxx ' ： Ignore ' xxx ' Case lookup .

zip 、 tar Instructions ：

1、zip xx.zip + Address ： By default, only one layer of surface is packaged , The package file name is xx.zip,+r Recursive packaging .

2、unzip xx.zip ： decompression xx.zip file .

3、unzip xx.zip -d + Address ： Unzip to this address .

-z ： Pack it up gzif Format

-f ： Use the document name , Followed by the document name

-c ： pack

-x ： decompression

tar pack / Compress , Do not open view .

4、tar czf xx.tgz ： Pack it up tgz Type file .

5、tar xzf xx.tgz -C xx/ ： Unzip to xx Under the path .

6、tar tf xx.tgz ： Do not decompress to view .

-t ： see

alias 、bc 、uname 、history Instructions ：

1、alias my='ls-al' ： Another name , hold  'ls-al' The name for my.

2、bc ： Floating point operation -- Linux Calculator

3、uname -r ： View information about your computer and operating system , can -a To view more .

4、history ： View history command .

Create delete user adduser 、 userdel 、file 、shutdowm command ：

1 、 Create user ：1、adduser xx New user name 2、passwd xx Input password （ No echo ）

Change the password of the existing account directly passwd that will do .

2 、 Delete user ：userdel -r xx Delete xx user .

3、file xxx ： View the file properties .

4、shutdowm ： To turn it off .

Hot key ：

1、Tab ： Quick completion .

2、Tab both parties ： Prompt command .

3、 Up and down keys ： History commands .

4、ctrl + d ： Fallback user .

5、ctrl + c ： Stop .

6、ctrl + R： Keyword search history command .