Chmod Calculator
Calculate Unix file permissions using checkboxes or numeric input.
rwxr-xr-x
| Read (4) | Write (2) | Execute (1) | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Other |
chmod 755 filename
Calculate Unix file permissions using checkboxes or numeric input.
| Read (4) | Write (2) | Execute (1) | |
|---|---|---|---|
| Owner | |||
| Group | |||
| Other |
Unix and Linux file permissions control who can read, write, and execute files and directories. Every file has three permission groups: owner, group, and others. Each group can be granted read (r), write (w), and execute (x) permissions independently. The chmod command is used to change these permissions, and it accepts both numeric (octal) and symbolic notation. This calculator helps you convert between the two formats instantly.
In numeric notation, each permission has a value: read is 4, write is 2, and execute is 1. These values are summed for each group to produce a three-digit number. For example, 755 means the owner has full permissions (7 = 4+2+1), while group and others have read and execute permissions (5 = 4+1). In symbolic notation, the same permission is written as rwxr-xr-x, where each character position represents a specific permission.
Always apply the principle of least privilege when setting file permissions. Grant only the minimum permissions necessary for a file or directory to function correctly. Avoid using 777 in production environments, as it allows any user on the system to read, modify, and execute the file.