Chmod 550 Explained
Chmod 550: owner and group can read and execute, others have no access. Secure read-only executable shared with a team.
Permission
550
r-xr-x---
chmod 550 filename
Permission Breakdown
| Role | Read (4) | Write (2) | Execute (1) | Octal | Meaning |
|---|---|---|---|---|---|
| Owner | r | - | x | 5 | read, execute |
| Group | r | - | x | 5 | read, execute |
| Others | - | - | - | 0 | no permissions |
Visual Permission Grid
Detailed Explanation
The permission 550 allows the owner and group to read and execute while blocking all access for others.
Octal breakdown:
- 5 (Owner): read (4) + execute (1) = read and execute
- 5 (Group): read (4) + execute (1) = read and execute
- 0 (Others): no access
In symbolic notation this is r-xr-x---. The owner and group members can read and execute the file. Nobody can modify it (not even the owner without changing permissions first). Others have no access.
This permission creates a read-only, executable file shared between the owner and group. It is useful for protected system utilities or scripts that should be used by a specific team but never modified on the running system. Modifications require explicit permission changes, adding a safety layer against accidental edits.
Use Case
Used for shared read-only scripts and utilities in team environments where both the owner and team should use the tools but nobody should accidentally modify them.