670
rw-rwx---
-rw-rwx---
chmod 670 — the rw-rwx--- permission
670 is rw-rwx---. The owner gets rw, and everyone else is shut out.
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 | ✓ | ✓ | · |
| Group7 | ✓ | ✓ | ✓ |
| Others0 | · | · | · |
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-rwx---
- ls -l (file)
- -rw-rwx---
- ls -l (directory)
- drw-rwx---
- chmod symbolic form
- chmod u=rw,g=rwx,o=
- Command
- chmod 670 <file>
- Binary
- 110111000
- Decimal
- 440
- umask (directory)
- 107
- umask (file)
- Not reachable — new files never start with the execute bit
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 670 mean?
It is rw-rwx---. ls -l shows a file as -rw-rwx--- and a directory as drw-rwx---.
Q. How is 670 written in rwx form?
It is the same as chmod u=rw,g=rwx,o=.
Q. What can other people do with 670?
Nothing. Only the owner and the group get in.
Q. Which umask produces 670?
107 for directories. For files it cannot be reached by umask alone, since new files never carry the execute bit.