chmod 400 meaning

400 r--------

The owner can read; the group and everyone else can do nothing.

When to use 400

Read-only private files, such as an AWS .pem key: only the owner can read them.

What each digit allows

Read = 4, write = 2, execute = 1. Each digit is the sum for one group of users.

Who	Digit	Symbolic	Read	Write	Execute
Owner (u)	4	r--	Yes	No	No
Group (g)	0	---	No	No	No
Others (o)	0	---	No	No	No

On a folder, read lists its contents, write adds or deletes files in it, and execute lets you open it (cd into it).

Commands

One file or folder, a folder with everything inside it, or only the files inside a folder:

chmod 400 file.php
chmod -R 400 folder/
find folder/ -type f -exec chmod 400 {} +

In cPanel: File Manager → right-click → Change Permissions, and tick the boxes until the number shows 400.

Try other permissions

Tick or untick the boxes to see the number, the symbolic form and the command.

	Read	Write	Execute
Owner
Group
Everyone else

Special bits (setuid, setgid, sticky)

setuid setgid sticky

Common values

Octal

Symbolic

Command

-R

Compare

Frequently asked questions

What does chmod 400 mean?

Each digit is the sum of read (4), write (2) and execute (1), for the owner, the group and everyone else. 400 = 4 / 0 / 0, so the owner can read; the group and everyone else can do nothing (r--------).

Should I use 400 for files or for folders?

400 suits files. A folder needs execute before anyone can open it, so folders usually get 755 (or 775 when your group must write).

How do I set 400 in cPanel?

In File Manager, right-click the file or folder, choose Change Permissions, and tick the boxes so the number shows 400. Over SSH: chmod 400 path (add -R to include everything inside a folder).