Linux Permission Octal Calculator
Toggle read, write and execute for owner, group and others. The octal number, symbolic notation and chmod command update live, or type an octal value to see which boxes it turns on.
Step 1: Pick permissions
Owner
Group
Others
Read 4
Write 2
Execute 1
Presets:
Warning: 777 gives everyone full read, write and execute access. Anyone on the system can read, change or delete this file. Use 755 for scripts and 644 for files instead.
Please enter 3 digits, each from 0 to 7.
Step 2: Result
Octal
755
Symbolic
rwxr-xr-x
Plain meaning
Owner can do everything, group and others can read and run.
Replace filename with your file name. Add -R after chmod to apply to a folder and everything inside it.
Common values
| Octal | Symbolic | Used for |
|---|---|---|
| 644 | rw-r--r-- | Regular files like documents and config files |
| 755 | rwxr-xr-x | Scripts and programs that must run |
| 600 | rw------- | Private files only the owner may read, like SSH keys |
| 700 | rwx------ | Private folders and scripts only the owner may use |
| 777 | rwxrwxrwx | Dangerous, everyone has full access, avoid |
How it works
Every file on Linux has 9 permission bits: read, write and execute for the owner, the group, and everyone else.
- Read is worth 4, write is worth 2, execute is worth 1. Add the values in each column to get one octal digit: read plus execute is 4 plus 1, which is 5.
- The three columns (owner, group, others) become three digits, for example 755.
- Symbolic notation writes the same thing with letters: rwx for full access, a dash - where a permission is missing, like rwxr-xr-x for 755.
- Reverse mode does the math backwards: each octal digit is split into its 4, 2 and 1 parts and the matching boxes are checked.
- The chmod command applies the number to a file: chmod 755 script.sh makes a script readable and runnable by everyone but changeable only by the owner.
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