The permissions are read (r), write (w), and execute (x).
这些权限就是读（r），写（w）和执行（x）。
The modes are read (r), write (w), or execute(x).
模式是读 (r)、写 (w)或执行 (x)。
'r' (the default) indicates that you want to read data from the file.
'r '(默认值)表示从文件读取数据。
R: The user has Read permissions to.
r：用户对有读权限。
R: The user has Read permissions to.
r：用户对有读权限。
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