[Linux] common Linux commands

Many common commands in Linux must be mastered. Here we will share some common basic commands that I learned when I started Linux, and hope to help you.

This is what I sorted out from laruence's book. I hope it will not involve copyright issues.

1. Date command

2. calendar display command: Cal

3. Easy to use calculator: BC

Why does 10/100 change to 0? This is because BC outputs only Integers by default. If you want to output the number of digits under the decimal point, you must execute scale = number, which is the number of decimal places, for example:

4. Key keys: [Tab], [CTRL]-C, and [CTRL]-d

[Tab] press the key to enable "command completion" instead of "file completion ".

[CTRL]-C: press the button to stop the current program 』

[CTRL]-D keys --- usually represent the end of the keyboard input (end of file, EOF end ofinput). In addition, it can also be used to replace exit

5. Man

Exit Q,

Man-F Man

6. synchronize data to disk: sync

Enter sync, and data that has not been updated in the memory will be written to the hard disk. Therefore, this role makes it important before the system is shut down and restarted! It is best to execute multiple times!

7. Conventional shutdown command: Shutdown

In addition, you must note that the time parameter must be included in the Command; otherwise, shutdown will automatically jump to run-Level 1 (that is, the login situation maintained by a single user), which will hurt your mind! Below are examples of several time parameters:

Restart, shut down: reboot, halt, poweroff

8. Switch execution level: init

There are seven execution levels in Linux:

-- Run level 0: Shutdown

-- Run level 3: plain text mode

-- Run level 5: graphic interface mode

-- Run level 6: restart

 

Use the init command to switch the modes:

If you want to shut down the instance, you can use the following command to shut down the instance in addition to the shutdown-H now and poweroff commands:

9. Change the group to which the file belongs: chgrp

10. Change the file owner: chown

He can also modify the group name directly by clicking "modify ".

11. Change file permissions: chmod

You can use numbers or symbols to set permissions.

-- Permission for changing the number type:

 

-- Change the File Permission of the symbol type:

12. View version information.

13. Change directory: CD

14. display the current directory: pwd

15. Create a new directory: mkdir

 

It is not recommended to use the-P option frequently, because you are worried that if you typed the wrong word, the directory name will become messy.

 

16. Delete the "null" Directory: rmdir

17. display of files and directories: ls

18. Copy an archive or directory: CP

19. Remove an archive or directory: Rm

20. Move files and directories or rename them: MV

21. Get the path file name and directory name: basename, dirname

22. The first line displays the file content: Cat

23. Display Tac from the last line (we can see that TAC is a cat write backwards)

24. When displayed, the downstream output line number is NL.

25. display file content on one page and one page: More

26. Similar to more, but better than more, he can flip the page forward: less

27. Just look at the first few rows: Head

28. Just look at the last few lines: tail

29. Read File Content in binary format: OD

30. Modify the file time or create a new file: Touch

31. File preset permissions: umask

32. configuration file hidden attribute: chattr

33. Hide the file property: lsattr

34. Observed file type: File

35. Find the [execution block]: Which

36. Search for specific files: whereis

37. Search for specific files: locate

38. Find a specific file

39. compressing and reading compressed files: gzip and zcat

40. compressed files and read compressed files: Bzip2, bzcat

41. compressed files and compressed files read: Tar

 

 

Well, I am exhausted and finally finished it. I hope it will help you.