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chmod Calculator

Set Unix file permissions with checkboxes and get the chmod number (755) and letters (rwxr-xr-x), or type either. Includes setuid and sticky bit.

Permissions

ReadWriteRun
Owner
Group
Everyone else

Result

  • Commandchmod 755 file
  • Number755
  • Lettersrwxr-xr-x
  • ls -l-rwxr-xr-x
  • umask for new folders022
  • Owner: read, write, run
  • Group: read, run
  • Everyone else: read, run

Shortcuts: Ctrl+Enter run · Ctrl+Shift+C copy result · / search (use ⌘ on Mac)

Free Online chmod Calculator

Tick the permissions you want and see the chmod number and the letters. Or type 755 or rwxr-xr-x and see what it allows. It gives developers a quick browser-based way to solve a focused chmod calculator task before moving the result into a project.

How to use the calculator

Tick Read, Write and Run for the owner, the group and everyone else. The number and letters update. Copy the command and run it on your server.

Typing a mode

Type a number such as 644, nine letters such as rw-r--r--, or a change such as u=rwx,g=rx,o=r.

Common mistakes

  • Giving a folder read but not run permission: nobody can enter it. Folders need run (x).
  • Making private keys readable by others: SSH refuses keys that are not 600.

Frequently asked questions

What do the three numbers mean?
Owner, group and everyone else, in that order. Each is the sum of read (4), write (2) and run (1). So 7 is all three, 5 is read and run, 4 is read only.
Which mode should I use?
644 for ordinary files (owner can edit, others can read), 755 for programs and folders, 600 for private files such as SSH keys and 700 for private folders.
Why is 777 a bad idea?
It lets every user and every process on the machine change the file. Almost every problem that seems to need 777 is really an owner or group problem: fix that with chown.
What are setuid, setgid and sticky?
Special bits: setuid and setgid run a program as its owner or group, and the sticky bit on a shared folder lets only owners delete their own files (used for /tmp).
How do I use this chmod calculator tool?
Use the interactive controls above; processing stays in your browser and the result is intended as a practical starting point for development work.

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