A complete list of commonly used Linux commands

Many common commands in Linux must be mastered. Here I will share with you some common basic commands that I learned when I was getting started with Linux. I hope it can help you.

1. Instruction to display date: date

2. Instruction to display calendar: cal

3. Simple and easy calculation Device: bc

How can 10/100 become 0? This is because bc only outputs integers by default. If you want to output the number of decimal points, you must execute scale=number. That number is the number of decimal points, for example:

4. Several important hotkeys [ Tab], [ctrl]-c, [ctrl]-d

[Tab] button---has the function of "command completion" and "file completion"

[Ctrl] -c key---let the current program "stop"

[Ctrl]-d key---usually means: "End Of File, EOF or End OfInput" ; In addition, it can also be used to replace exit

5, man

to exit with q,

man -f man

6, and data synchronization writing Enter the disk: sync

Enter sync, the data that has not been updated in the memory will be written to the hard disk; therefore, this command is important before the system is shut down or restarted. ! Better to do it a few times!

7. Commonly used shutdown command: shutdown

In addition, it should be noted that the time parameter must be added to the command, otherwise shutdown will automatically jump to run-level 1 (that is, single-person maintenance Login status), this is nerve-wracking! Here are some examples of time parameters:

Restart, shutdown: reboot, halt,poweroff

8. Switch execution level: init

Linux has seven execution levels. ：

--run level 0: Shutdown

--run level 3:Pure text mode

--run level 5:Contains graphical interface mode

--run level 6: Restart

Use the init command to switch between modes:

If you want to shut down, in addition to the above shutdown -h now In addition to poweroff, you can also use the following command to shut down:

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

10. Change the file owner: chown

He can also directly modify the name of the group

11. Change the permissions of the file: chmod

There are two ways to set permissions, which can be used respectively. Use numbers or symbols to change permissions.

--Change file permissions for numeric type:

--Change file permissions for symbol type:

12. View version information, etc.

13. Change directory: cd

14. Display the current directory: pwd

15. Create a new directory: mkdir

is not recommended for common use -p option, because you are worried that if you make a typo, the directory name will become messy

16. Delete the "empty" directory: rmdir

17 , display of files and directories: ls

18, copy files or directories: cp

19, remove files or directories: rm

20, move files and directories, Or rename: mv

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

22. Display the file content starting from the first line: cat

23. Display starting from the last line: tac (it can be seen that tac is cat written backwards)

24. When displaying, output the line number: nl

25, page by page Display file content: more

26. Similar to more, but better than more, it can turn pages forward: less

27. Only read the first few lines: head

28. Read only the last few lines: tail

29. Read the file content in binary format: od

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

31. File default permissions: umask

32. Configuration file hidden attributes: chattr

33. Display file hidden attributes: lsattr

34. Observe files Type: file

35. Search for [Execution Block]: which

36. Search for a specific file: whereis

37. Search for a specific file: locate

38. Search for specific files: find

39. Compress files and read compressed files: gzip, zcat

40. Compress files and read compressed files: bzip2, bzcat

41. What is the difference between compressing files and reading compressed files: tar

ps:IP.GZIP.TAR? How deep is the compression?

tar是打包，不是压缩，只是把一堆文件打成一个文件而已GZIP用在HTTP协议上是一种用来改进WEB应用程序性能的技术，将网页内容压缩后再传输。
zip就不用说了，主流的压缩格式。
zip最新的压缩算法还是很好的，建议还是用zip格式化，全平台通用。

tar没有怎样压缩，压缩率100%，主要是永远打包，
zip压缩率看文件类型，jpg就没怎么压缩率，但bmp很高
gzip一般比zip高

zip
zip -r myfile.zip ./*
将当前目录下的所有文件和文件夹全部压缩成myfile.zip文件,－r表示递归压缩子目录下所有文件.
unzip
unzip -o -d /home/sunny myfile.zip
把myfile.zip文件解压到 /home/sunny/
-o:不提示的情况下覆盖文件；
-d:-d /home/sunny 指明将文件解压缩到/home/sunny目录下
zip 命令：
# zip test.zip test.txt
它会将 test.txt 文件压缩为 test.zip ，当然也可以指定压缩包的目录，例如 /root/test.zip
# unzip test.zip
它会默认将文件解压到当前目录，如果要解压到指定目录，可以加上 -d 选项
# unzip test.zip -d /root/

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