664
rw-rw-r--
-rw-rw-r--
chmod 664 — the rw-rw-r-- permission
Files several people edit together.
664 is rw-rw-r--. The owner gets rw, and everyone else gets r.
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 | |
|---|---|---|---|
| Owner6 | ✓ | ✓ | · |
| Group6 | ✓ | ✓ | · |
| Others4 | ✓ | · | · |
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-r--
- ls -l (file)
- -rw-rw-r--
- ls -l (directory)
- drw-rw-r--
- chmod symbolic form
- chmod u=rw,g=rw,o=r
- Command
- chmod 664 <file>
- Binary
- 110110100
- Decimal
- 436
- umask (directory)
- 113
- umask (file)
- 002
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 664 mean?
It is rw-rw-r--. ls -l shows a file as -rw-rw-r-- and a directory as drw-rw-r--.
Q. How is 664 written in rwx form?
It is the same as chmod u=rw,g=rw,o=r.
Q. What can other people do with 664?
They get r--.
Q. Which umask produces 664?
113 for directories. The same 002 gives it for files too.