Detailed analysis of Linux folder execution Permissions

What is the Linux folder execution permission? First, users familiar with Linux know that Linux has three permissions: r, w, and x. If you are not familiar with Linux, it doesn't matter. I will talk about the Linux folder execution permission from the file permission.

Linux's File Permission is one of the greatest guarantees for Linux's security performance. Some may know that, many methods of attacking windows are to obtain the permissions of creating users through vulnerabilities to control computers. in Linux, the Root account has the maximum permissions and can do everything, other users can only have all the permissions of their own files and the permissions granted to the files by the members of the Change Group. The following describes the file permissions.

Read Permission R. Simply put, it is the permission to open the file to view the content. On the web server, if the file does not have the permission to open, the web server considers the file does not exist and sends the 404 file not found error, it is represented by number 4.

Write Permission W. If a file does not have the write permission, the file cannot be changed. If the folder does not have the write permission, a new file cannot be created in the folder, which is indicated by the number 2.

Execution permission X. To execute a program file, you must have the execution permission; otherwise, the program file cannot be executed. Opening a folder is also executed, so the folder cannot be opened if it has no execution permission. It is represented by number 1.

Note the x mark! If the file name is a directory, for example, the. ssh directory:

Drwx ------ 2 root 4096 Feb 10 00:44. ssh

It can be seen that this is a directory, and only root can read, write, and execute. But if it is the style below, can anyone other than root enter this directory?

Drwxr -- r -- 2 root 4096 Feb 10 00:44. ssh

Success! It seems OK! Because there is a readable [r! "Error !』 The answer is that non-root users cannot access the. ssh directory. Why? Because the relationship between x and the directory is very important. If you cannot execute any commands under the directory, you will naturally not be able to execute commands such as ls and cd, therefore, please note that if you want to open a directory for some people to come in, please remember to open the x attribute of this directory to others!

Now we know what the Linux folder execution permission is like!

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