Chmod 444 Explained
Chmod 444: read-only for everyone. Nobody can write or execute. Used for published files that must remain unmodified.
Permission
444
r--r--r--
chmod 444 filename
Permission Breakdown
| Role | Read (4) | Write (2) | Execute (1) | Octal | Meaning |
|---|---|---|---|---|---|
| Owner | r | - | - | 4 | read |
| Group | r | - | - | 4 | read |
| Others | r | - | - | 4 | read |
Visual Permission Grid
Detailed Explanation
The permission 444 makes a file universally read-only. Everyone can read it, but nobody can write to or execute it.
Octal breakdown:
- 4 (Owner): read (4) only
- 4 (Group): read (4) only
- 4 (Others): read (4) only
In symbolic notation this is r--r--r--. All users on the system can read the file, but no one can modify or execute it. The owner must change the permissions before making any edits.
This permission is used for files that should be publicly readable but strictly protected against modification. Configuration reference files, published documentation, and legal notices are common candidates. It serves as a safeguard on shared systems where multiple users or automated processes might interact with the file.
Use Case
Used for published documentation files, license files, reference configurations, and any file that should be world-readable but immutable without explicit permission change.