Ubuntu Chmod Command: Change File Permissions

The chmod command is used to change the permissions of a file or directory. Its basic syntax is:

chmod [选项] 模式 文件或目录

Common options include:

1. -R: Recursively change the permissions of a file or directory.
2. -v: Display detailed information about the modifications.
3. Display only files whose permissions have been modified.

The permissions can be represented in numerical form or symbol form. Numerical permissions are as follows:

1. No permission
2. 1: Execution rights
3. 2: Writing permission
4. 4: Read access

Different combinations of these numbers can be used to represent various levels of access. For example, 777 represents all permissions being fully open.

Symbolic forms of authority include:

1. u: owner of the file or directory
2. Group ownership of a file or directory
3. o: other users
4. a: All users

In addition, you can use “+”, “-“, and “=” to indicate increasing, decreasing, or setting permissions. For example, chmod +x file means giving the file “file” the permission to execute.

In short, the chmod command allows users to flexibly modify the permission settings of files or directories as needed.