What are best practices for using umask command?

The umask command is a vital utility in Unix-like operating systems that sets default file permission settings for newly created files and directories. Understanding and correctly applying umask can significantly enhance system security and ensure that files have appropriate access controls. Here are some best practices when using the umask command:

• Know your default umask: Before changing the umask, check the current settings using the umask command without any arguments.
• Set umask globally: For system-wide changes, set umask in the global configuration files like `/etc/profile` or in specific user profiles.
• Understand permission bits: Familiarize yourself with the default permission bits for files and directories. For instance, the default permission for files is typically 666 (read/write) and for directories is 777 (read/write/execute).
• Use octal notation carefully: The umask value is subtracted from the default permission; choose the right umask to achieve the desired permission level. A common umask is 022, which allows read and execute permissions for others but restricts write permissions.
• Test changes: After changing the umask, test it by creating files and directories to ensure the correct permissions are applied.
• Document your changes: Keep a record of any umask changes for both system administrators and users to reference in the future.

By following these best practices, you can use umask effectively to control file permissions and enhance your system's security.