FILEATTRIBUTEREADONLY

FILEATTRIBUTEREADONLY is a constant or flag used in many programming environments and operating systems to represent the read-only attribute of a file. When a file has the read-only attribute set, it means that the file's contents cannot be modified, deleted, or overwritten by standard user operations. This attribute is a security and data integrity mechanism designed to prevent accidental or unauthorized changes to important files.

Operating systems like Windows, macOS, and Linux all support file attributes, including a read-only flag. In Windows, for instance, this attribute can be toggled through the file's properties dialog or programmatically using functions like GetFileAttributes and SetFileAttributes. In Unix-like systems, the read-only status is typically managed through file permissions, where removing write permissions for the owner, group, or others effectively makes the file read-only for those entities.

The FILEATTRIBUTEREADONLY constant is often used in code to check if a file is read-only before attempting to write to it, or to programmatically set or unset this attribute. This prevents errors and ensures that applications behave as expected when interacting with files that should not be altered. For example, system configuration files are often protected with the read-only attribute to prevent users from inadvertently corrupting critical system settings. When a user attempts to save changes to a read-only file in an application, the application will usually prompt the user to save the file with a new name or to remove the read-only attribute.