Unix Permission Calculator

Unix file permissions assign access rights for three distinct user target roles: Owner (user), Group, and Others (world). For each role, three access privileges can be granted: Read (r = 4), Write (w = 2), and Execute (x = 1). Adding the privilege scores produces an octal digit between 0 and 7 for each role.

Octal notation uses numerical digits (e.g. 755 or 644) where each digit represents the combined sum of Read (4), Write (2), and Execute (1) permissions. Symbolic notation uses a 9-character string representation (e.g. rwxr-xr-x) indicating granted privileges with letters 'r', 'w', 'x' or hyphen '-' when denied.

SUID (Set User ID, +4000) causes an executable file to run with the permissions of the file owner (e.g. root). SGID (Set Group ID, +2000) causes executables to run with group rights or directories to automatically pass group ownership down to new files. Sticky Bit (+1000) restricts file deletion in world-writable directories (like /tmp) to the file creator only.

Permission 777 (rwxrwxrwx) grants read, write, and execute permissions to everyone on the operating system. Any user, background service, or malicious script can alter, replace, or delete files in a 777 directory, posing a severe security hazard.

Numeric syntax sets exact explicit permission bits across all roles at once (e.g. chmod 755 file). Symbolic syntax modifies specific permission bits relative to existing rights (e.g. chmod u+rwx,g+rx,o+rx file or chmod o-w file). Both syntaxes are generated live by this calculator.

Yes, 100%. Toolzeno performs all permission math, conversion, validation, and command generation locally inside your browser client-side. No permission data or server inputs are ever transmitted.