chmod 440
chmod 440 is r--r-----.
What 440 grants
| Who | Digit | Permissions | Adds up as |
|---|---|---|---|
| Owner | 4 | read | 4 = 4 |
| Group | 4 | read | 4 = 4 |
| Others | 0 | no access | 0 |
When 440 is the right answer
Read-only for the owner and the group. Useful for a credentials file that a service account needs to read through group membership but nothing should modify at runtime.
The command
chmod 440 filename
chmod -R 440 directory/Note that nobody has the execute bit here, so this value cannot be used on a directory that anyone needs to enter. On a directory, execute grants traversal rather than the right to run something.
How it is written elsewhere
| Octal | 440 |
| Symbolic | r--r----- |
As a file in ls -l | -r--r----- |
As a directory in ls -l | dr--r----- |
| Binary | 100 100 000 |
| World-writable | No |
Frequently asked questions
What does chmod 440 mean?
It sets owner to read, group to read, others to no access. In symbolic notation that is r--r-----.
How do I apply 440?
Run chmod 440 filename. Add -R to apply it to a directory and everything inside, though be careful: a recursive numeric chmod marks every file the same way, which is rarely correct for a mixed tree of files and directories.
Is 440 safe?
It grants no write access outside the owner, so it is a reasonable setting as long as the owner is the account you intend.
What is 440 in symbolic notation?
r--r-----. Written as ls -l shows it, with a leading file-type character, an ordinary file would appear as -r--r----- and a directory as dr--r-----.