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Developer Utility
Linux Chmod Permissions Calculator
Visually calculate octal values, symbolic representations, and special bits (SUID, SGID, Sticky Bit) with instant copyable terminal commands.
Octal Notation
755
3-digit: 755
Symbolic Notation
-rwxr-xr-x
ls -l file format
Generated Terminal Command
$ chmod 755 /var/www/html
Ready to run in bash/zsh
File / Folder:
Interactive Permission MatrixClick checkboxes to toggle
Owner (User)Value: 7
GroupValue: 5
Others (Public)Value: 5
Special Permissions (Advanced Linux Flags)
Common Linux Permission Presets
How Linux File Permissions Work (The 3x3 Octal System)
In Unix and Linux operating systems, file access is enforced through a discretionary access control (DAC) model. Every file and directory is associated with an Owner (the user who created it), a Group (a collection of authorized users), and Others (any user with an account on the machine).
Read (r = 4)
Files: View file contents. Folders: Read directory filenames with ls.
Write (w = 2)
Files: Modify, edit, or truncate file data. Folders: Create, rename, or delete files inside.
Execute (x = 1)
Files: Execute as an executable program or shell script. Folders: Traverse or cd into the directory.
Quick Octal Values Reference Table
Download 1-Page PDF| Octal | Binary | Symbolic | Capabilities |
|---|---|---|---|
| 0 | 000 | --- | No permissions |
| 1 | 001 | --x | Execute only |
| 2 | 010 | -w- | Write only |
| 3 | 011 | -wx | Write and execute |
| 4 | 100 | r-- | Read only |
| 5 | 101 | r-x | Read and execute |
| 6 | 110 | rw- | Read and write |
| 7 | 111 | rwx | Read, write, and execute |
Frequently Asked Questions (FAQ)
Chmod 755 (rwxr-xr-x) grants the owner full Read, Write, and Execute rights, while Group and Others can only Read and Execute. It is standard for directories and executable scripts. Chmod 644 (rw-r--r--) grants the owner Read and Write access, while Group and Others can only Read. It is standard for non-executable public web assets (HTML, CSS, images).
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