Chmod 755 Explained
Learn chmod 755: owner has full access, group and others can read and execute. The standard permission for directories and scripts.
Permission
755
rwxr-xr-x
chmod 755 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 755 is one of the most commonly used permission sets in Unix systems. It gives the owner full control while allowing others to read and execute.
Octal breakdown:
- 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-x. The owner can read, modify, and execute the file. Group members and all other users can read and execute but cannot modify it. For directories, the execute bit allows users to traverse into the directory and access files within it.
This is the default permission for most directories created by system tools and package managers. It is also the standard for shell scripts, CGI scripts, and any executable that needs to be run by the web server or other users. The key security benefit is that only the owner can modify the file, preventing unauthorized changes while still allowing access.
Use Case
Standard permission for web server directories, executable scripts, and program binaries. Apache and Nginx typically require 755 on directories to serve content correctly.