Chmod 1755 Explained
Chmod 1755: sticky bit with standard 755 permissions. Only the file owner can delete files in this directory.
Permission
1755
rwxr-xr-t
chmod 1755 filename
Permission Breakdown
| Role | Read (4) | Write (2) | Execute (1) | Octal | Meaning |
|---|---|---|---|---|---|
| Owner | r | w | x | 7 | read, write, execute |
| Group | r | - | x | 5 | read, execute |
| Others | r | - | x | 5 | read, execute |
Visual Permission Grid
Detailed Explanation
The permission 1755 adds the sticky bit to standard 755 permissions, creating a directory where everyone can read and traverse but only file owners can delete their files.
Octal breakdown:
- 1 (Special): sticky bit set
- 7 (Owner): read (4) + write (2) + execute (1) = full access
- 5 (Group): read (4) + execute (1) = read and execute
- 5 (Others): read (4) + execute (1) = read and execute
In symbolic notation this is rwxr-xr-t. The t in the others execute position indicates the sticky bit is set.
Unlike 1777, this permission does not give group and others write access to the directory itself. Only the owner can create files. The sticky bit here provides an additional safeguard on the owner's files. This is less common than 1777 but is used when the directory owner wants to create files that cannot be deleted by other users who might gain write access through other means (such as ACLs or future permission changes).
Use Case
Used for application-managed directories where the sticky bit provides extra protection for the owner's files against deletion by other processes or users.