405
r-----r-x
-r-----r-x
chmod 405 — the r-----r-x permission
405 is r-----r-x. The owner gets r, and everyone else gets rx.
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 | |
|---|---|---|---|
| Owner4 | ✓ | · | · |
| Group0 | · | · | · |
| Others5 | ✓ | · | ✓ |
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-----r-x
- ls -l (file)
- -r-----r-x
- ls -l (directory)
- dr-----r-x
- chmod symbolic form
- chmod u=r,g=,o=rx
- Command
- chmod 405 <file>
- Binary
- 100000101
- Decimal
- 261
- umask (directory)
- 372
- 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 405 mean?
It is r-----r-x. ls -l shows a file as -r-----r-x and a directory as dr-----r-x.
Q. How is 405 written in rwx form?
It is the same as chmod u=r,g=,o=rx.
Q. What can other people do with 405?
They get r-x.
Q. Which umask produces 405?
372 for directories. For files it cannot be reached by umask alone, since new files never carry the execute bit.