Chmod Calculator

File permissions are fundamental to Linux and Unix security. The chmod command controls who can read, write, and execute files, but the numeric notation can be confusing at first. This calculator provides a visual interface where you check boxes for each permission and see the resulting numeric and symbolic notation update in real time.

Permissions are divided into three categories: Owner (the file creator), Group (users in the file's group), and Others (everyone else). Each category can have Read, Write, and Execute permissions. The numeric representation uses octal digits: read is 4, write is 2, execute is 1, and the sum gives the digit for each category. For example, 755 means the owner has all permissions (7=4+2+1), while group and others can read and execute (5=4+1).

The reverse mode lets you enter a numeric value like 755 and see the checkboxes update automatically. This is useful for understanding existing permissions or learning how chmod works. The generated command can be copied and pasted directly into your terminal.