Chmod 2770 Explained
Chmod 2770: SGID with full owner and group access, no access for others. New files inherit group ownership in a private shared directory.
Permission
2770
rwxrws---
chmod 2770 filename
Permission Breakdown
| Role | Read (4) | Write (2) | Execute (1) | Octal | Meaning |
|---|---|---|---|---|---|
| Owner | r | w | x | 7 | read, write, execute |
| Group | r | w | x | 7 | read, write, execute |
| Others | - | - | - | 0 | no permissions |
Visual Permission Grid
Detailed Explanation
The permission 2770 combines full owner and group access with the SGID bit, while blocking all access for others.
Octal breakdown:
- 2 (Special): SGID bit set
- 7 (Owner): read (4) + write (2) + execute (1) = full access
- 7 (Group): read (4) + write (2) + execute (1) = full access
- 0 (Others): no access
In symbolic notation this is rwxrws---. The s in the group execute position indicates SGID is active.
This permission creates a private, collaborative directory. All team members in the group have full access, and the SGID bit ensures that any new files or subdirectories created inside will inherit the directory's group, maintaining consistent group ownership. Users outside the group cannot access the directory at all.
This is the gold standard for secure team collaboration directories on multi-user systems. It solves the common problem where files created by different users end up with different group ownership, which can break access for other team members.
Use Case
Used for private shared project directories, version control repositories, and collaborative workspaces where consistent group ownership is critical and outside access must be blocked.