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CHMOD Configurator

Calculate Linux file permissions using checkboxes, octal numbers, or symbolic notation.

Owner

Group

Public

-rwxr-xr-x

Command Line Example

chmod 755 filename
Or apply recursively to all files and directories inside a folder:
chmod -R 755 foldername/

How to use this tool

  1. Identify the three permission classes

    Linux permissions apply to three classes: Owner (the user who created the file), Group (a collection of users sharing permissions), and Public (everyone else). Decide what each class should be able to do.

  2. Choose Read, Write, and Execute for each class

    For each class, toggle Read (4), Write (2), and Execute (1). The calculator updates the octal code and symbolic notation live as you check or uncheck boxes.

  3. Read the octal code

    Add the values for each class to get a single digit: Read + Write + Execute = 7, Read + Execute = 5, Read only = 4. Concatenate the three digits (Owner, Group, Public) to get the octal code like 755 or 644.

  4. Run the chmod command

    Apply the permissions in your terminal with `chmod <octal> <file>`, for example `chmod 755 script.sh`. Add the -R flag to apply recursively to a directory and everything inside it.

About this tool

The CHMOD Configurator makes Linux file permissions visual and easy to understand. Instead of memorizing octal numbers, you can just click the exact permissions you want to grant for the Owner, Group, and Public.

As you toggle the checkboxes, the calculator instantly updates the exact octal code (like 755 or 644) and symbolic notation you need to run in your terminal. You can also type an octal number directly into the input box to reverse calculate it and see exactly what permissions it grants.

Understanding the three classes

Linux permissions are applied to three distinct classes of users. The 'Owner' is the user account that created the file. The 'Group' is a collection of users who share the same permissions. 'Public' (or Others) applies to literally everyone else on the system.

When to use -R (Recursive)

By default, running a chmod command only changes the permission of that exact file or folder. If you want to change a folder and every single file inside of it simultaneously, add the -R flag (e.g. `chmod -R 755 myfolder`).

Popular permission scenarios

Pre-explained permission sets with octal, symbolic, and use-case guidance.

chmod 755
rwxr-xr-x, standard for directories and scripts
View details →
chmod 644
rw-r--r--, standard for static files
View details →
chmod 600
rw-------, required for SSH private keys
View details →

Frequently asked questions

What does chmod 777 mean?
A permission of 777 means that the file or directory is completely readable, writable, and executable by everyone (Owner, Group, and Public). This is highly insecure and should only be used as a temporary troubleshooting step, never in production.
What does chmod 755 mean?
A permission of 755 is standard for web server directories and executable scripts. It means the Owner has full rights (Read, Write, Execute), while the Group and Public can only Read and Execute (but not modify) the file.
What does chmod 644 mean?
A permission of 644 is standard for web server files (like HTML or PHP files). It means the Owner can Read and Write the file, but everyone else can only Read it.
How do the numbers 4, 2, and 1 work?
Linux file permissions use a bitwise system: 4 stands for Read, 2 stands for Write, and 1 stands for Execute. When you add them together, you get unique combinations. For example, Read + Execute = 4 + 1 = 5. Read + Write + Execute = 4 + 2 + 1 = 7.

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