Free tool · 🔐 chmod permissions calculator
755 or 644?Click it, see it.
The permission reference every Linux admin keeps open: octal to symbolic, special bits explained, and the commands for the common cases (web directories, SSH keys, cron scripts).
Rule of thumb: directories 755, files 644, private keys 600, scripts 750. Never 777 on a web server.
What it checks
Everything we would look at first on a client call.
Free, no sign-up, no email gate. If the report shows red, the fix is written next to it — and we are one click away if you would rather we did it.
- Octal ↔ symbolic, live both ways
- setuid / setgid / sticky explained
- chmod, chown, find recipes for web roots, keys and scripts
- umask equivalent
FAQ
Common questions
What does 755 mean?
Owner: read, write, execute; group and others: read and execute. Standard for directories and scripts.
Why is 777 bad?
Anyone on the system (including a compromised web process) can modify the file. Use ownership + 755/644 instead.