Common operating commands of Linux

Command is often used

 Log off users ：logout or exit
	 restart ：reboot or shutdown -r now
	 To turn it off ：halt or shutdown -h now
	 see liunx Kernel version ：uname 
		-r： Display the release number 
		-a： View all information 
		-man： Displays the type of machine used 
		-i： Displays the required hardware platform 
		-v： Display the operating system version number 
		-n： Check the network node host name 
	 Check the disk space size and remaining space size of the file system ：df
	 How long has the display system been running ：uptime
	 View the current system memory usage ：free
	 Exit open document ：esc : q 
	 Inquire about CPU Detailed hardware information ：cat /pros/cpuinf
	 Dynamically display the data of the current process ：top
	 View login log information ：last
	 View the logged-in user information ：w [ user name ]
	 Display monthly calendar or annual calendar ：cal
		cal 09 2020： see 2020 year 9 Calendar of the month 
	 Display or set the current date and time ：date
	 Display all user names of users currently logged in to the system ：who
	 Show that I am currently logged in to the system user terminal ：who am i
	 Count the number of lines in a given file 、 Number of words and characters ：wc [-lw] [-c]  file name 
		l： The statistical number of rows 
		w： Count characters 
		c： Count the number of bytes 
	 Clear the screen ：clear
	 View all history commands ：history | more
	 Execute the commands in the historical command list ：! n（n Is the number in the historical command list ）
	> and >> ：“>” Means to write the input information directly ,“>>” It means that the output information is written into 
		ls > t.txt ： Enter the current information into t.txt In file 

Switch 6 Virtual terminals

Ctrl+Alt+F1： Graphical interface terminal 
Ctrl+Alt+F2~F6：5 Virtual terminals 

Common directory

/： root directory , At the top of the file system 
/bin： Store common commands , Ordinary users can also perform 
/lib： Library file storage directory 
/dev： Store equipment files 
/etc： Store most configuration files and subdirectories of the system 
/tmp： Storage of temporary documents 
/boot： Store contents and guide system program files 
/usr： The directory where the system stores programs 
/home： The default storage location of the home directory of ordinary users 
/lost+found：EXT2 or EXT3 File system , Fragmented files caused by unexpected system crash or accidental shutdown 
/opt： Can choose , Store some software packages or third-party applications 
/root： System administrator home directory 
/mnt： Used to temporarily mount file systems , Provide default mount points for some devices 
/proc： Virtual file system , The files in this directory are images in memory 
/sbin： Save the system administrator or root User's command file 
/var： Usually save content that changes frequently , Such as system logs and mail files 

Common shortcut key

Tab： Automatic completion 
Ctrl+U： Clear the current position to the first character of the line 
Ctrl+K： Clear the current position to the end of the line 
Ctrl+L： Clear the screen 
Ctrl+C： To terminate the execution of an order 
Ctrl+D： Save and exit 
pageup： The previous page 
pagedown： The next page 
Ctrl+U： Cut the contents in front of the cursor 
Ctrl+Y： Paste 
Ctrl+E： Move the cursor to the end of the line 
Ctrl+A： Move cursor to the beginning of line 
ALT+F： Jump to the next space 
ALT+B： Jump back to the last space 
ALT+Backspace： Delete the previous word 
Ctrl+W： Cut the word after the cursor 
Shift+Insert： Paste text into the terminal 

1、 Directory switching command

cd  Toggle directory 
	cd .   Current working directory 
	cd ..  Parent directory 
	cd -   Previous working directory 
	cd ~   User home directory 
pwd  Display the current directory 
su  user name ： Switch to different users  （exit Exit current user ）
ls [ Options ] [ Directory name ]： View information in the directory 
	ls -a       List all files in the directory , Include implied documents 
	ls -l       List file details （ Abbreviation ：ll）
	ls -h       And '-l' Together , Easy to read format output file size 
	ls -m       Compact the list of files separated by commas 
	ls -R       Recursively display the files in each subdirectory of the specified directory 
	ls -i       Display the inode number of the file in the first column of the output 
	ls --help   Display help information 
	 Catalog color ：
		 Blue ： Catalog （ Folder ）
		 gray ： Ordinary documents 
		 green ： Executable file 
		 Red ： Compressed files 
		 sky blue ： Link to the file 

2、 Document management order

mkdir [ Options ]  Directory name ： Create directory 
	mkdir -m	 Set the permission mode when creating a directory 
	mkdir -p	 Create each directory specified in the directory structure , Create a directory if it doesn't exist , If the directory already exists, it will not be overwritten 
	mkdir -v	 or --verbose： Every time you create a new directory, the message 
	mkdir -help	 Display help information 
	 Example ：
		mkdir  Catalog + file name 1  Catalog + file name 2
		mkdir -p xx/yy/zz  Create multiple folders in succession 
		mkdir -m 766 xxx  give xxx Folder 766 jurisdiction 
touch  file name ： Create a new blank text file 
cp [ Options ]  Source file   Target file ： Copy directories or files 
	-a： Keep links 、 File attribute , When copying directories, you can recursively copy directories 
	-f： If the target file or directory already exists , Then cover it , No hint （force）
	-i： If the target file or directory already exists , Then prompt the user , You can use letters y confirm , The other letters are denial 
	-r： duplicate catalog , Copy the files and subdirectories under the source directory to the target directory 
	 Example ：
		cp -r xx yy/ : Copy xx Folder path yy Under the folder 
		cp -a xx yy/ : Keep the original properties 
mv [ Options ]  Source file   Target file ： Move or rename directories or files 
	 Example ：
		mv /xx/1.txt /yy/2.txt : Move xx Under the folder 1.txt To yy Folder and rename it 2.txt
rm [ Options ]  Target file ： Delete file 
	-f： If the target file or directory already exists , Then cover it with swallows , No hint （force）
	 Example ：
		rm 1.txt： Delete 1.txt file 
		rm -r xx： Delete xx Folder and prompt 
		rm -rf xx： Delete xx Folder does not prompt 
		rm -rf xx yy dd： Delete xx yy dds Folder does not prompt 
rmdir [ Options ]  Directory name ： Delete empty directory , And you must delete it in the parent directory 
	-p		 Delete the specified tree 
	-v		--verbose Output diagnostic information during directory deletion 
	--help	 Display command help 
find  Find the path to the directory   Search for conditional options   Setting of search conditions ： It is used to find the files that meet the conditions under the relative path 
	-name：  Find the file by filename 
	-user：  Find files by user name 
	-type：  Find files by file type 
	-size：  Find files by file size 
	-atime： Find the file by its last access date （ Company ： God ）
	-mtime： Find the file by the last modification date of the file （ Company ： God ）
	-newer： Find files that are newer than the specified file 
	-amin：  Find files that have been accessed within a specified time （ Company ： minute ）
	-cmin：  Find files that have been changed within a specified time （ Venerable position ： minute ）
	-perm：  Find files that match the specified permission values 
	 Example ：
		find / -name xxx： Look in the root directory xxx The file of 
info  command ： Find an overview of specific commands 
man  command ： Find an overview of specific commands 

3、 File permissions

 There are three kinds of users with access rights ：
 File owner (Owner)： Owner of file 
 When the user (Group)： Users in the same group that the file belongs to 
 Other users (Others)： Other users who can access the file 
 Representation of access to files or directories ：
r( read )： Allow reading of file contents or column directories 
w( Write )： Allows you to modify the contents of a file or create 、 Delete file 
x( Can be executed or found )： Allow the execution of files or allow the use of cd Command to enter the directory 
-( No authority )： It is not allowed to read the file 、 Modification and implementation 
 for example ：
				 file type    File owner    When the user    Other users 
				   d      rwx      r-x     r--
	 Binary representation               111      101     100
	 Octal representation                7        5       4
 Modify file permissions ：
① Modify permissions in alphabetical form ：
	chomd [ Options ]  Pattern [, Pattern ]  file name  
		 User object ：
			u：user Represent user , The owner of a file or directory 
			g：group Represents the same group of users , That is, it has the same group as the file group ID All users of 
			o：others Means other users 
			a：all It means all the above users 
		 Operation symbol ：
			+： Add a permission 
			-： Cancel a permission 
			=： Give the given permission and cancel all other permissions 
		 Operating authority ：
			r： Can be read 
			w： Can write 
			x： Executable 
		 for example ：
			chmod u+x,g+w,o-r file1   to file1 Add executable permissions to the file owner , Add writable permissions to users in the same group , Other users cancel the read permission 
			chmod a=rw file2          to file2 All users of the file are granted read and write permission 
② Modify permissions in digital form ：
	chmod  Octal mode   file name 
		 for example ：
			chomd 664 file1 (110 110 100)  to file1 The owner of the file grants read and write permission , Users in the same group are granted read and write permission , Other users give readable permission 
			chomd 700 file2 (111 000 000)  to file2 The owner of the file grants readable, writable and executable permissions , Users in the same group are not authorized , Other users are not authorized 

4、vi Editor

vi  file name  -》  Enter command mode 
	vi +  file name            Open the file and stop the cursor at the beginning of the last line 
	vi + n  file name        Open the file, and the cursor stops at n Line beginning 
	vi - r  file name         Files recovered after the system crashed 
	vi + / word   file name     Find... From the file “ word ” First occurrence , The cursor stops at the beginning of the line changing 
 In command mode, press "a(append)、i(insert)、o" Enter input mode , Press... In input mode and last line mode "esc" Enter command mode , In command mode, press ":" Enter last line mode 
 Cursor movement ：( Command line mode )
	 On   Next   Left   Right ：			↑ ↓ ← →
	 Turn the previous page ：				Page Down or Ctrl+F
	 Turn the next page ：				Page Up or Ctrl+B
	 Jump to the top of the line ：			Home or "^" or "0"
	 Jump to end of line ：			End or "$"
	 Move right # Characters ：			#→
	 Move left # Characters ：			#←
	 Jump to the beginning of the line of the file ：		1G or gg
	 Jump to the last line of the file ：		G
	 Jump to file No # That's ok ：		#G
	 Show line numbers in the editor ：	:set nu
	 Cancel the line number in the editor ：	:set nonu
 Copy 、 Paste 、 Delete 、 Move ：( Command line mode )
	 Delete a single character at the cursor ：				x or Del
	 Delete the current cursor line ：				dd
	 Delete... From the cursor # Row content ：			#dd
	 Delete all characters from the current cursor to the first line ：	d^
	 Delete all characters from the current cursor to the end of the line ：	d$
	 Copy the entire contents of the current line to the clipboard ：		yy
	 Copy from cursor # Row content ：			#yy
	 Copy # To # Line to the current cursor position ：		:#,# co .
	 Copy # To # Row to # Where the line is ：			:#,# co #
	 After pasting the contents of the buffer to the cursor position ：p
	 Move # To # Line text to # That's ok ：				:#,# m #
	 Move # To # Line text to filename In file ：	:#,# w filename
	 Move # To # Line text is appended to filename In file ：:#,# w >> filename
 File content search ：( Last row mode )
	 Find the string in the file from top to bottom "word"：	/word
	 Find the string in the file from bottom to top "word"：	?word
	 Locate the next matching found string ：		n
	 Locate the last matching searched string ：		N
 Undo editor ：
	 Press once to cancel the most recent operation , Press multiple times to restore ：	u
	 Used to cancel all current edits ：				U
 Save files and exit vi Editor ：( Command line mode )
	 Save the file ：		:w or :w /root/newfile( Save as other file )
	 sign out ：			:q( Unmodified exit ) or :q!( Forced exit )
	 Save file and exit ：:wq
 File content replacement ：( Command line mode )
	 The first string found in the current row "old" Replace with "new"：	:s /old/new
	 All strings found in the current line "old" Replace with "new"：		:s /old/new/g
	 In the line number "#,#" Replace all strings in scope "old" by "new"：		:#,# s/old/new/g
	 Replace all strings throughout the file "old" by "new"：		:% s/old/new/g
	 Prompt the user to confirm for each replacement action ：						:s /old/new/c

5、 see file

more  file name ： Browse all contents of the file ( Space page 、 Enter displays line by line , Exit automatically after display )
less  file name ： Browse all contents of the file ( Will not exit after display ,:q sign out )
cat [ Options ]  file name 
	-n   Number the number of output lines 
	-b   Number the number of non blank lines output 
	-s   When encountering more than two consecutive blank lines , Replace with a blank line 
head [ Options ]  file name ： Look at the first few lines of the file （ Before default 10 That's ok ）
	-#  See the former # That's ok 
tail [ Options ]  file name ： Look at the last few lines of the file （ After default 10 That's ok ）
	-#  Check out the last # That's ok 
grep  keyword   Find the range ： Find the matching string , Output all the contents of the line where the matching string is located 
	 example ：grep student /etc/passd     lookup student In the file /etc/passd Position in 

（1） Check the status of open ports 
	 Query open ports  netstat -anp
	 Query whether the specified port is open  firewall-cmd --query-port=666/tcp
	 Tips  yes, Open for indication ;no Indicates not on .
（2） View firewall status 
	 View firewall status  systemctl status firewalld
	 Turn on the firewall  systemctl start firewalld  
	 Turn off firewall  systemctl stop firewalld
	 Turn on the firewall  service firewalld start 
	 If you can't open it 
	 First use ：systemctl unmask firewalld.service 
	 then ：systemctl start firewalld.service
（3） Foreign development port 
	 Check whether the port you want to open is open ：
		firewall-cmd --query-port=6379/tcp
	 Add the specified port to be opened ：
		firewall-cmd --add-port=123/tcp --permanent
	 Overload into the added port ：
		firewall-cmd --reload
	 Query whether the specified port is opened successfully ：
		firewall-cmd --query-port=123/tcp
	 Remove the specified port ：
		firewall-cmd --permanent --remove-port=123/tcp