What this tool does
Unix permissions are three sets of read, write and execute bits, plus setuid, setgid and sticky. This calculator keeps the octal number, symbolic string and chmod command in sync, so you can move between them without memorising the bit table.
How to use it
- Type an octal mode or tick the permission boxes.
- Check the symbolic form and the special bits.
- Copy the chmod command.
Questions
755 or 644?
755 gives the owner full access and everyone else read/execute — typical for directories and executables. 644 gives the owner write and everyone else read — typical for files.
What do setuid, setgid and sticky do?
They change execution identity or deletion rules. Use them deliberately; they are security-sensitive.
Does this handle directories?
The bits are the same. The leading character in the symbolic form is shown as - for a regular file.