chmod 666
chmod 666 is rw-rw-rw-.
What 666 grants
| Who | Digit | Permissions | Adds up as |
|---|---|---|---|
| Owner | 6 | read, write | 4 + 2 = 6 |
| Group | 6 | read, write | 4 + 2 = 6 |
| Others | 6 | read, write | 4 + 2 = 6 |
When 666 is the right answer
Everyone can read and write. There is almost no legitimate use for this on a real file — if several accounts need write access, put them in a group and use 660.
The command
chmod 666 filename
chmod -R 666 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 | 666 |
| Symbolic | rw-rw-rw- |
As a file in ls -l | -rw-rw-rw- |
As a directory in ls -l | drw-rw-rw- |
| Binary | 110 110 110 |
| World-writable | Yes — any user on the system can modify this |
Frequently asked questions
What does chmod 666 mean?
It sets owner to read, write, group to read, write, others to read, write. In symbolic notation that is rw-rw-rw-.
How do I apply 666?
Run chmod 666 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 666 safe?
It is world-writable, so any account on the system can modify the contents. That is only appropriate for a shared scratch area, and even then the sticky bit should normally be set as well. For anything else, grant access through a group instead.
What is 666 in symbolic notation?
rw-rw-rw-. Written as ls -l shows it, with a leading file-type character, an ordinary file would appear as -rw-rw-rw- and a directory as drw-rw-rw-.