chmod 444
r--r--r--Safe when used as intended
Everyone can read; nobody can write or execute.
444 is read-only for everyone — the owner included. It guards against accidental edits and deletions by scripts and editors, while still letting anyone read the file.
It isn't a lock: the owner (and root) can always chmod it back.
Permission by permission
| Who | Read | Write | Execute | Digit | Means |
|---|---|---|---|---|---|
| owner | ✓ | — | — | 4 | read only |
| group | ✓ | — | — | 4 | read only |
| others | ✓ | — | — | 4 | read only |
- In
ls -l:-r--r--r--for a file,dr--r--r--for a directory. - Symbolic form:
u=r,g=r,o=r - New files get this mode when the umask is
222.
Use it for
- Reference data and generated files that must not be edited by hand.
- Published files you want protected from accidental overwrite.
Avoid it for
- Secrets — everyone can read them. Use
400. - Files a tool regenerates: it will fail with 'Permission denied'.
Commands
chmod 444 path
set this mode on a file or directory
chmod u=r,g=r,o=r path
the same, written symbolically
find path -type f -exec chmod 444 {} +apply it to every file in a tree, leaving the directories alone
stat -c '%a %A %n' path
check the current mode on Linux (macOS: stat -f '%Lp %Sp %N' path)
Try variations
444
-r--r--r--
| Who | read | write | execute | Digit |
|---|---|---|---|---|
| owner | 4 | |||
| group | 4 | |||
| others | 4 |
The owner can read only; the group can read only; everyone else can read only.
chmod 444 file
chmod u=r,g=r,o=r file
Frequently asked questions
Can the owner still modify a 444 file?
Not directly — writes fail. But the owner can chmod it back to 644 at any time, so treat 444 as a safety catch, not security.
Related modes