What is chmod in Linux?

Chmod (change mode) is the Linux command used to change file and directory access permissions.

How do octal permissions work in Linux?

Octal numbers combine bit values: Read=4, Write=2, Execute=1. The sum forms a digit for Owner, Group, and Others.

What does chmod 755 mean?

Owner has full access (rwx = 7), Group and Others can read and execute (r-x = 5).

What does chmod 644 mean?

Owner can read and write (rw- = 6), Group and Others can only read (r-- = 4).

Why is chmod 777 dangerous?

It grants every user and process on the system full permission to modify or delete the file.

Are permissions evaluated locally in browser memory?

Yes, ScanSuite's calculator computes octal and symbolic modes entirely client-side.

What permission is required for SSH private keys?

SSH requires `600` (`rw-------`) or `400` (`r--------`) on private key files.

How do I make a shell script executable?

Run `chmod +x script.sh` or `chmod 755 script.sh`.

What is the difference between chmod and chown?

Chmod changes WHAT actions users can perform; chown changes WHO owns the file or group.

Why can I not access a folder with 644 permissions?

Directories require Execute (`x`) permission (e.g. 755) to allow entering and listing contents.

How do I apply permissions recursively to all subfolders?

Use the `-R` flag: `chmod -R 755 /path/to/directory`.

What is symbolic notation in chmod?

Representing permissions with characters like `u+rwx,g+rx,o+rx` or `rwxr-xr-x`.

What does the leading 0 in chmod 0755 mean?

The leading zero indicates standard octal formatting or special flags (SetUID, SetGID, Sticky Bit).

What is the sticky bit in Linux permissions?

A special permission flag (e.g. in `/tmp`) that prevents users from deleting files owned by others.

Is this chmod calculator free to use?

Yes, ScanSuite provides unlimited free chmod calculations without registration.

What permissions should I set for WordPress wp-config.php?

Set `600` or `640` to protect database credentials from unauthorized reading.

Can I copy generated terminal commands directly?

Yes, click the copy button next to the generated command to paste into your terminal.

What does chmod -x do?

Removes execution permissions from the file or directory.

Free Linux Chmod Calculator & Permissions Tool

A chmod calculator is a system administration utility that translates file permissions between human-readable interactive checkboxes, 3-digit octal codes (such as 755 or 644), and symbolic string notation (`rwxr-xr-x`), generating copy-paste Linux `chmod` terminal commands.

Toggle read (4), write (2), and execute (1) permission checkboxes for User (owner), Group, and Other (world) to instantly generate the matching octal code (e.g. `755`), symbolic mode string (`rwxr-xr-x`), and terminal command (`chmod 755 filename`).

Linux and Unix operating systems enforce multi-user security through access control flags assigned to files and directories. Every filesystem object defines distinct read (`r`), write (`w`), and execute (`x`) permissions for three scopes: Owner (User), Group, and Others (World).

ScanSuite's free online chmod calculator simplifies permission management. Toggle permission checkboxes interactively to view live updates across octal numbers (e.g., `755`, `644`, `700`), symbolic strings, and ready-to-run terminal commands without memorizing bitwise octal math or risking insecure `777` defaults.

ScanSuite's free Linux chmod calculator translates file permissions between octal codes, symbolic notation, and interactive checkboxes. Easily generate secure terminal commands for server administration.

Frequently Asked Questions

What is chmod in Linux?: Chmod (change mode) is the Linux command used to change file and directory access permissions.
How do octal permissions work in Linux?: Octal numbers combine bit values: Read=4, Write=2, Execute=1. The sum forms a digit for Owner, Group, and Others.
What does chmod 755 mean?: Owner has full access (rwx = 7), Group and Others can read and execute (r-x = 5).
What does chmod 644 mean?: Owner can read and write (rw- = 6), Group and Others can only read (r-- = 4).
Why is chmod 777 dangerous?: It grants every user and process on the system full permission to modify or delete the file.
Are permissions evaluated locally in browser memory?: Yes, ScanSuite's calculator computes octal and symbolic modes entirely client-side.