File permissions explained (chmod, 644, 755 and why they matter)
Every file on a Linux web server has three permission flags - read (r), write (w), execute (x) - for three audiences: the file's owner, the owner's group, and everyone else. The permission is written as a 3-digit octal number like 644 or 755.
Reading the digits
| Digit | Means | Audience |
|---|---|---|
| 7 = read + write + execute | 4+2+1 | first digit = owner |
| 6 = read + write | 4+2 | second digit = group |
| 5 = read + execute | 4+1 | third digit = everyone else |
| 4 = read only | 4 | |
| 0 = no access | 0 |
The values you actually need
- 644 for files - owner can read/write, everyone else can read. Default for HTML, CSS, JS, images, PHP files.
- 755 for folders - owner can read/write/list-contents, everyone else can read/list. Default for every directory.
- 600 for sensitive config files like
wp-config.phpor.env- only owner can read. - 400 for SSH private keys - read-only by owner, nothing else.
What NOT to do
Never set anything to 777. Some old tutorials suggest "if it does not work, chmod 777" - this gives every script on the server full access to your file. Most plugin upload errors are caused by something else (PHP memory, file size limits) - 777 just opens a security hole.
Changing permissions
- cPanel File Manager: right-click → Permissions → tick the boxes or type the octal value.
- FileZilla: right-click the file → File Permissions → enter the value.
- SSH:
chmod 644 filename.phporchmod 755 foldername.
