Chmod 660 Explained
Chmod 660: owner and group have read and write access, others have none. Used for shared data files in secure environments.
Permission
660
rw-rw----
chmod 660 filename
Permission Breakdown
| Role | Read (4) | Write (2) | Execute (1) | Octal | Meaning |
|---|---|---|---|---|---|
| Owner | r | w | - | 6 | read, write |
| Group | r | w | - | 6 | read, write |
| Others | - | - | - | 0 | no permissions |
Visual Permission Grid
Detailed Explanation
The permission 660 grants read and write access to both the owner and group, while blocking all access for others.
Octal breakdown:
- 6 (Owner): read (4) + write (2) = read and write
- 6 (Group): read (4) + write (2) = read and write
- 0 (Others): no access
In symbolic notation this is rw-rw----. The owner and group members can read and modify the file. Other users cannot access it at all. Nobody can execute the file directly.
This permission is useful for shared data files that contain sensitive information. Database files, shared log files, and collaborative documents on multi-user systems often use 660. It allows team members to work together on files while ensuring that other system users cannot read or modify the content.
Use Case
Used for shared database files (e.g., SQLite), collaborative data files, and log files where both the application (owner) and monitoring tools (group) need read-write access.