Chmod Calculator
Calculate Unix/Linux file permissions with this interactive tool. Understand octal values and symbolic notation.
Permissions Calculator
| Category | Read (4) |
Write (2) |
Execute (1) |
Value |
|---|---|---|---|---|
| Owner (User) | ||||
| Group | ||||
| Others |
Octal Value
Symbolic Notation
Example Command
Understanding Unix Permissions
Permission Values
- Read (r) - View file contents or list directory
- Write (w) - Modify file or directory contents
- Execute (x) - Run file or traverse directory
Common Permission Values
- 755 rwxr-xr-x Common for executables
- 644 rw-r--r-- Common for files
- 777 rwxrwxrwx Full access for all
Why Use Our Chmod Calculator?
Instant Calculation
Get octal values and symbolic notation in real-time as you toggle permissions.
Visual Learning
Understand how Unix permissions work through interactive examples.
Practical Examples
See the exact chmod command to use for your selected permissions.
Mobile Friendly
Works perfectly on all devices - desktop, tablet, and mobile.
No Server Needed
All calculations happen in your browser for complete privacy.
Educational
Learn Unix permissions through interactive exploration.
How Unix Permissions Work
Permission Classes
Unix file permissions are divided into three classes:
- Owner - The user who owns the file
- Group - Users who are in the file's group
- Others - All other users
Permission Types
Each class can be granted three types of permissions:
- Read (r) - View file contents or list directory
- Write (w) - Modify file or directory contents
- Execute (x) - Run file or traverse directory
Octal Notation
Permissions are often represented as octal (base-8) numbers:
Read = 4, Write = 2, Execute = 1
These values are added together for each class. For example, read+write+execute = 4+2+1 = 7.
Symbolic Notation
Permissions can also be represented symbolically:
rwxr-xr-x
The first three characters represent owner permissions, the next three represent group permissions, and the last three represent others permissions.
Frequently Asked Questions
What is chmod?
Chmod (change mode) is a Unix/Linux command used to change the permissions of files and directories.
What does "755" mean in chmod?
755 means the owner has read, write, and execute permissions (7), while group and others have read and execute permissions (5).
What's the difference between 755 and 644?
755 gives execute permission to everyone, while 644 doesn't give execute permission to anyone. 755 is commonly used for directories and executables, while 644 is used for regular files.
How do I make a file executable?
You can use chmod +x filename to add execute permission for all users, or chmod 755 filename to set specific permissions.
What does "rwxr-xr-x" mean?
This symbolic notation means the owner has read, write, and execute permissions (rwx), while group and others have read and execute permissions (r-x).