1. Run the ls command

View files and folders visible in the current directory and their permissions. Common parameters are as follows: -l List view -al View all files and folders, including hidden files and foldersCopy the code
[root@qinshengfei bin]# ls --color displays in color
[root@qinshengfei bin]# ls -l List directory files in detail
[root@qinshengfei bin]# ls -a Displays all files, including hidden files
[root@qinshengfei bin]# ls-al list displays all files
[root@qinshengfei bin]# the ls - al | more will show directory content distribution
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2, mkdir create folder

Common parameters: Direct folder nameCopy the code
[root@qinshengfei /home]# mkdir test

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3. PWD Displays the current working directory

[root@qinshengfei bin]# pwd/usr/bin <== Displays the current working directoryCopy the code

4. CD Switch the directory

[root@qinshengfei /root]# cd .. <== Go back to the previous directory
[root@qinshengfei /]# CD <== go back to home
[root@qinshengfei root]# CD /usr/bin <== go to /usr/bin

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5. Rmdir Deletes the specified directory

If the directory to be deleted contains files or folders that cannot be moved, you need to add the -rf parameter to force the deletion.Copy the code
[root@qinshengfei /root]# rmdir./test <== Delete directory
[root@qinshengfei /root]# rmdir./test2 -rf <== delete directories and subdirectories, files
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6. Rm deletes the command file

[root@qinshengfei /root]# rm test

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Cp means copy. For example, if we want to copy the.bashrc file to /home, we can:

[root@qinshengfei /root]# cp .bashrc /home

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8. Mv Move files and folders

[root@qinshengfei /root]# mv test.txt /home

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9. Cat prints the contents of the file on the console, for example, to print the mysql configuration file to the control

[root@qinshengfei /mysql.conf.d]# cat mysqld.cnf

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10. Tail Displays file contents by line

[root@qinshengfei /mysql.conf.d]# tail -n 5 mysqld.cnf

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11, less

The less command is used to view files. It's faster to use, and you won't inadvertently modify files. With fewer cursors, you can use the up and down arrow keys, the PgUp and PgDn keys, and the Home and End keys to scroll back and forth through the file. Press Q to exit less.Copy the code
[root@qinshengfei /mysql.conf.d]# less log.txt

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12. Grep pipe to output the specified file content

Use ps - aux inquiry process, for example, we just need to know the tomcat is not running, you can use the pipeline instruction "|" to join the grep command operation at the same time.Copy the code
[root@qinshengfei /]# ps -aux|grep tomcat

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13, find the file

[root@qinshengfei /]# find / -name bin


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14. Tar -cvf compressed file

[root@qinshengfei /root]# tar -zcvf app.tar.gz app

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15. Gzip compression

The compress command is similar to the compress command. Just zip the suffix.gz!Copy the code
[root@qinshengfei /root]# gzip -d xxxxx.gz

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16. Unzip the decompressed file

[root@qinshengfei /root]Zip unzip a file called 'app.zip'

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18. Exit Exit the login


[root@qinshengfei /root]# exit
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19. Ping is the same as ping in Windows


[root@qinshengfei /root]# ping baidu.com
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20. Telnet tests that the port on the target machine is open

[root@qinshengfei /root]# telnet 47.2.30.289 8080

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21. Who Displays all the current users

[root@qinshengfei /root]# who

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22. Su to switch users

[root@qinshengfei /root]# su qinshengfei

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Uname Displays important information about the system, such as kernel name, host name, kernel version, processor type, etc. Use uname -a to view all information.

[root@qinshengfei /]# uname -aLinux qinshengfei 4.18.0-80.11.2. El8_0. X86_64#1 SMP Tue Sep 24 11:32:19 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
[root@qinshengfei /]# 

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24, alias

Using the alias command, you can give a command or sequence of commands its own name. You can then enter your abbreviation, and the Shell will execute commands or sequences of commands for you.Copy the code
[root@qinshengfei /]# alias pf="ps -e | grep $1"
[root@qinshengfei /]# pf tomcat

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25, chmod modify file and folder permissions command

0: No permission
1: Execute permission
2: Write permission
3: Write and execute permissions
4: Read permission
5: Read and execute permissions
6: Read and write permissions
7: Read, write and execute permissions
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[root@qinshengfei /]# chmod 777 app-r <== -r

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26 and chown

You can use chown to change the owner or group of a file, or both. Owner and group names must be provided, separated by: characters.Copy the code
[root@qinshengfei /]# chown dave:mary example.txt
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27, curl

The curl command is a tool for retrieving information and files from a uniform resource Locator (URL) or Internet address.Copy the code
[root@qinshengfei /]# curl http://www.baidu.com index.html

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28, echo

The echo command prints the text string to the terminal window. You can also print the string to a file.Copy the code
[root@qinshengfei /]# echo "hello world"
hello world
[root@qinshengfei /]# 
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29, free

The free command gives you a summary of your computer's memory usage. It does this for both main random access memory (RAM) and swap memory. The -h (human) option is used to provide human-friendly numbers and units. Without this option, numbers are in bytes.Copy the code
[root@qinshengfei /]# free
              total        used        free      shared  buff/cache   available
Mem:        8000348     1554508     4549432         576     1896408     6194856
Swap:             0           0           0
[root@qinshengfei /]# 

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30, the history,

The history command lists the previous commands you issued on the command line. You can repeat any command in history by typing an exclamation point! And command numbers in the history list.Copy the code
[root@qinshengfei /]# 
[root@qinshengfei /]# history
    1  yum install docker
    2  yum install nginx
    3  yum -y install docker-ce
   

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31, kill

We’ll use the ps and grep tips from the section on alias commands above. We can search the shutter process and get its PID as follows:

[root@qinshengfei /]# ps -ef|grep nginx
root     31884 22980  0 16:19 pts/0    00:00:00 grep --color=auto nginx
root     32400     1  0 Feb18 ?        00:00:00 nginx: master process /usr/sbin/nginx
nginx    32401 32400  0 Feb18 ?        00:00:00 nginx: worker process
nginx    32402 32400  0 Feb18 ?        00:00:00 nginx: worker process
[root@qinshengfei /]# kill -9 32400

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32 and passwd

The passwd command enables you to change the user password. Simply type passwd to change your own password.Copy the code
[root@qinshengfei /]# sudo passwd mary

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33, SSH,

Use the SSH command to establish a connection to a remote Linux machine and log in to your account. To establish a connection, you must provide your user name and the IP address or domain name of the remote computer. In this example, user Mary logs in to the computer at 192.168.4.23. Once the connection is established, she will be asked to enter her password.Copy the code
[root@qinshengfei /]# ssh [email protected]
[email protected]'s password: 

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35. Df View the system disk usage

[root@qinshengfei /]# dfFilesystem 1K-blocks Used Available Use% Mounted on devtmpfs 3986836 0 3986836 0% /dev tmpfs 4000172 0 4000172 0% /dev/shm tmpfs 4000172 576 3999596 1% /run tmpfs 4000172 0 4000172 0% /sys/fs/cgroup /dev/vda1 52417516 4031296 48386220  8% / overlay 52417516 4031296 48386220 8% /var/lib/docker/overlay2/650e5470981551bdd57ee3f9da79da55ef5170d11017e282c318f801b5c5ac4b/merged tmpfs 800032 0 800032 0% /run/user/0 [root@qinshengfei /]# 

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36. Ps displays the system process

The ps command lists the processes that are running. Using ps without any options causes it to list the processes running in the current shell.Copy the code
[root@qinshengfei /]# ps
  PID TTY          TIME CMD
 9191 pts/0    00:00:00 ps
16776 pts/0    00:00:00 bash
17212 pts/0    00:00:00 mysql
22980 pts/0    00:00:00 bash
23524 pts/0    00:00:44 java
[root@qinshengfei /]# 

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To query the keyword process, you can use the pipeline command.Copy the code
[root@qinshengfei /]# ps -ef|grep nginx
root     10377 22980  0 16:26 pts/0    00:00:00 grep --color=auto nginx
root     32400     1  0 Feb18 ?        00:00:00 nginx: master process /usr/sbin/nginx
nginx    32401 32400  0 Feb18 ?        00:00:00 nginx: worker process
nginx    32402 32400  0 Feb18 ?        00:00:00 nginx: worker process
[root@qinshengfei /]# 

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37. Top Displays system processes

[root@qinshengfei /]# top
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38, Reboot the computer

[root@qinshengfei /]# reboot 
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39, shutdown

Using shutdown with no parameters will shut down the computer in one minute.

[root@qinshengfei /]# shutdown
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Use the now parameter to power off immediatelyCopy the code
[root@qinshengfei /]# shutdown -h now
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Restarting the system using -r has the same effect as restarting the system using reboot. Shutdown -r can be timedCopy the code
[root@qinshengfei /]# shutdown -r now
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40, yum!

Commands for installing software in centosCopy the code
[root@qinshengfei /]# yum install nginx
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