Chmod Calculator
Calculate Unix file permissions.
| Permission | Read | Write | Execute |
|---|---|---|---|
| Owner | |||
| Group | |||
| Other |
-rw-r--r--
Presets:
chmod 644 fileAbout the Chmod Calculator
Turns Unix file permissions into the octal number and the chmod command you need, in both directions. Tick read, write, and execute for owner, group, and others, and read off 644 or 755; or paste a mode and see what it actually grants. Faster and safer than reasoning about permission bits in your head at the wrong moment.
How to use the Chmod Calculator
- Tick the read, write, and execute boxes for owner, group, and others.
- Read the resulting octal value and symbolic notation.
- Copy the chmod command.
Frequently asked questions
- What does chmod 755 mean?
- Owner can read, write, and execute; group and others can read and execute but not write. It is the usual mode for directories and executable scripts.
- What does chmod 644 mean?
- Owner can read and write; everyone else can only read. This is the standard mode for ordinary files.
- How is the octal number derived?
- Read is 4, write is 2, execute is 1, summed per role. Owner, group, and others each get one digit, so 7 is 4+2+1 and 6 is 4+2.
- Why should I avoid chmod 777?
- It lets any user on the system write to the file, including replacing an executable with their own. It is almost never the right fix, and it is a standard finding in security audits.