Linux Chmod & File Permissions Calculator
Use this interactive calculator to generate Linux chmod octal numbers (e.g. 755, 644) and symbolic notation strings (e.g. -rwxr-xr-x). Toggle permission flags for User, Group, and Others or choose from built-in Linux server security presets.
Frequently Asked Questions
Q:What is Linux chmod?
chmod (change mode) is a system command in Linux/Unix operating systems used to alter the access permissions of files and directories. Permissions determine who can Read (r=4), Write (w=2), or Execute (x=1) a file.
Q:How do octal permissions work?
Octal permissions use a 3-digit number where the first digit represents the Owner (User), the second represents the Group, and the third represents Others (Public). Each digit is the sum of permissions: Read (4) + Write (2) + Execute (1). For example, 755 means Owner=7 (4+2+1), Group=5 (4+1), Others=5 (4+1).
Q:What are common Linux file permissions?
Common modes include: 755 (rwxr-xr-x) for web directory scripts and executables, 644 (rw-r--r--) for standard web files (HTML/CSS/JS), 600 (rw-------) for private SSH keys and passwords, and 777 (rwxrwxrwx) for temporary shared folders (use with caution).
Q:What is the difference between symbolic and octal notation?
Octal uses numbers like 755 or 644. Symbolic notation uses 9 characters representing r (read), w (write), x (execute), and - (no permission), grouped in sets of 3: -rwxr-xr-x.