What causes PermissionError?

Writing to a file owned by another user or root without write permission. Reading a file with mode 000 or otherwise restricted access. Trying to bind to a privileged port (below 1024) without elevated rights. Deleting a file in a directory where the current user lacks write permission.

← Errors

Python

PermissionError: What It Means and How to Fix It

Error reference

PermissionError

Language

Python

Severity

Medium

When it happens

PermissionError is raised when trying to perform a file or directory operation without the required permissions.

Potential fixes

Check file permissions with ls -l or Path.stat() before operating. Run the process with appropriate privileges if truly needed. Prefer writing to user-owned directories like the home directory or a temp folder.

Related errors

OSError FileNotFoundError

Deep dive

PermissionError is raised when trying to perform a file or directory operation without the required permissions. It is a subclass of OSError with errno set to EACCES or EPERM. This typically happens when a non-root process tries to access restricted system files.

Why it happens

•Writing to a file owned by another user or root without write permission.
•Reading a file with mode 000 or otherwise restricted access.
•Trying to bind to a privileged port (below 1024) without elevated rights.
•Deleting a file in a directory where the current user lacks write permission.

Potential fixes

Check file permissions with ls -l or Path.stat() before operating. Run the process with appropriate privileges if truly needed. Prefer writing to user-owned directories like the home directory or a temp folder.

Examples

Python

Code that triggers the error

with open("/etc/passwd", "w") as f:
    f.write("hacked")

Error output

PermissionError: [Errno 13] Permission denied: '/etc/passwd'

Fixed code

import os
from pathlib import Path

target = Path("output.txt")
try:
    target.write_text("data")
except PermissionError as e:
    print(f"Cannot write: {e}")

Practice in English

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