50 useful Linux Commands – Part 2

Hello everyone, in this two part tutorial, we will learn some very basic and useful Linux commands. So lets get started. For Part-1, check here

1. Check command history : “history” command is used viewing all the previous command.

    history

2. Search in command history: Lets say you want to search a specific keywords in previously runned commands. then you have to run:

    history | grep search_term

3. Write in a file: You can write a text in a file by running below command

   echo "Hello world!" > hello.txt

   Note: This command will create a file named “hello.txt” inside “Hello World!” written in it.

4. Create new file: For creating a new file, below command is used: eg: touch filename.filetype

    touch test.txt

5. Install new package: For install new package, apt install command is used. eg: apt install package_name

    apt install git
   
    apt install ftp

6. Remove package: To remove an installed package, you have to run:

    apt purge *git*

   Note: cp is copy command, then file name, finally directory where you want to copy the file

7. Start a service: If you want to run/start any service, you have to run below command: service service_name start

   eg: service apache start

8. Start a service at start up: To start or run a service in startup, you have to use “systemctl” command

    systemctl enable service_name

   Note: eg: systemctl anable ssh

9. Stop any service: To stop any service, you have to run

    service service_name stop

   Note: eg: service apache2 stop

10. Stop any startup service: To disable a startup service, you have to run:

     systemctl disable service

11. Check Service Statuses: Check service all service status :

    service --status-all

    Note: Running service will have “+” sign

12. Restart a service: To restart any service:

    systemctl restart service_name

13. Check service status: If you want to check any service status, run:

     systemctl status service_name

    Note: You have to run this command as super admin

14. Reload a service: If you want to reload any service without restarting it, only reload the configurations, run below command

     systemctl reload service_name

    Note: After running the command, you have to provide user name, password and password confirmation

15. Reload or restart: If you are not sure wheather to reload or restart, run below command, it will check itself if new configuration to load or to restart the service

     systemctl reload-or-restart service_name

    Note: Here we reading the “/etc/passwd” file, which contains all users info.

16. Change permission: “chmod” command is use to provide specific access to a file or folder. Afile may have read (r), write(w) or execute (x) permission. If you want to give execute permission to a file, you have to run:

     chmod +x script

    Note: Be careful of this file. Do not give full access to this file for security reason.

17. Exit terminal: For exit the current shell terminal, you have to run:

     exit

    Note: Such as, if you want to switch to user jhon, run “su john“

18. Turn off machine: If you want to turn off the machine, just run:

     shutdown

    Note: The default shutdown time is one minute, if you want to shutdown immediately, type: “shutdown now“

19. Unzip a zipped folder: To unzip/extract the contents of any zip folder, you have to run below command:

    unzip zipped_folder_name.zip

    Note: It will provide Interface Configuration related data

20. Show Processes: If you want to check running processes, you should use “htop” command. It may not be installed by default. Then just install it by typing “y”

     htop

21. Terminate any process: If any app is unresponsive, you can use “kill” command with process ID or application binary name. Such as:

     kill chrome 
    
     kill process_id

22. Remove a file and make it unrecoverable: To remove any file and make it unrecoverable, you have to run below command:

     shred file_name.extension

    Note: Be cautious before running this file

23. Print current user: To print current user, just run:

     whoami

24. Get location of any app: Get location of any app, run “where” command. eg:

     where php

25. Get word count of a text file:To get word count of a text file, run below command::

    wc text_file.txt

    Note: cp is copy command, then file name, finally directory where you want to copy the file

26. Update Packages list and Upgrade Packages: If you want to update all the packages list and also upgrade all the packages in one single command, you have to run

     apt update && apt upgrade

That’s all for today. In the first part, you will get 25 more basic Useful Linux commands. Keep learning folks!