Use explicit permission notations

When setting file permissions through system calls like chmod, always use explicit octal notation (with the 0o prefix) rather than decimal integers. Decimal integers in permission contexts can lead to unintended access rights, creating security vulnerabilities through incorrect file permissions.

For example, instead of:

os.chmod("foo", 644)  # Incorrect - decimal integer

Use:

os.chmod("foo", 0o644)  # Correct - explicit octal notation

The decimal value 644 is not equivalent to the octal value 0o644, and this mismatch can lead to improper permission settings that may expose sensitive files to unauthorized access. Always verify permission values in security-sensitive operations.