511
r-x--x--x
-r-x--x--x
chmod 511 — the r-x--x--x permission
511 is r-x--x--x. The owner gets rx, and everyone else gets x.
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 | |
|---|---|---|---|
| Owner5 | ✓ | · | ✓ |
| Group1 | · | · | ✓ |
| Others1 | · | · | ✓ |
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
- r-x--x--x
- ls -l (file)
- -r-x--x--x
- ls -l (directory)
- dr-x--x--x
- chmod symbolic form
- chmod u=rx,g=x,o=x
- Command
- chmod 511 <file>
- Binary
- 101001001
- Decimal
- 329
- umask (directory)
- 266
- 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 511 mean?
It is r-x--x--x. ls -l shows a file as -r-x--x--x and a directory as dr-x--x--x.
Q. How is 511 written in rwx form?
It is the same as chmod u=rx,g=x,o=x.
Q. What can other people do with 511?
They get --x.
Q. Which umask produces 511?
266 for directories. For files it cannot be reached by umask alone, since new files never carry the execute bit.