chmod 066 — the ---rw-rw- permission
066 is ---rw-rw-. The owner can do nothing, and everyone else gets rw. Anyone at all can change it.
Anyone can change it · The write bit is open to everyone. Anybody who reaches this machine can change the contents, so keep it away from web folders and config files.
Who can do what
Three rows for owner, group and others; three columns for read, write and execute. On a folder that last one means the right to go inside.
| Read | Write | Execute | |
|---|---|---|---|
| Owner0 | · | · | · |
| Group6 | ✓ | ✓ | · |
| Others6 | ✓ | ✓ | · |
On a folder the execute bit means going inside. With read but no execute you can list the names yet open nothing in it.
- Symbolic
- ---rw-rw-
- ls -l (file)
- ----rw-rw-
- ls -l (directory)
- d---rw-rw-
- chmod symbolic form
- chmod u=,g=rw,o=rw
- Command
- chmod 066 <file>
- Binary
- 000110110
- Decimal
- 54
- umask (directory)
- 711
- umask (file)
- 600
One digit away
How to read this
- Read is 4, write 2, execute 1; add them for one digit. 7 is 4+2+1, 5 is 4+1.
- The digits are owner, group, others, left to right.
- umask is what gets taken away: from 777 for directories, from 666 for files.
- Special bits (setuid 4000, setgid 2000, sticky 1000) add a fourth digit in front — /tmp is 1777.
Frequently asked questions
Q. What does chmod 066 mean?
It is ---rw-rw-. ls -l shows a file as ----rw-rw- and a directory as d---rw-rw-.
Q. How is 066 written in rwx form?
It is the same as chmod u=,g=rw,o=rw.
Q. What can other people do with 066?
They get rw- — write included, so anyone can change the contents.
Q. Which umask produces 066?
711 for directories. The same 600 gives it for files too.