| Who | Read (4) | Write (2) | Execute (1) |
|---|---|---|---|
| Owner | |||
| Group | |||
| Other |
| Octal | Symbolic | Typical use |
|---|---|---|
| 644 | rw-r--r-- | Regular files: owner can edit, everyone can read. |
| 755 | rwxr-xr-x | Directories and scripts: owner full, others read/execute. |
| 600 | rw------- | Private files (SSH keys, config): owner only. |
| 700 | rwx------ | Private directories/scripts: owner only. |
| 666 | rw-rw-rw- | Read/write for everyone (rarely a good idea). |
| 777 | rwxrwxrwx | Full access for everyone (avoid on shared systems). |
| 640 | rw-r----- | Owner edits, group reads, others none. |
| 444 | r--r--r-- | Read-only for everyone. |
On Unix and Linux, every file has permissions for three groups — the owner, the group and everyone else (other) — and each group can have read (4), write (2) and execute (1). Adding those values per group gives a digit from 0 to 7, and the three digits together form the octal mode you pass to chmod, such as 755.
Tick the boxes to build the mode and the octal, symbolic (rwxr-xr-x) form and ready-to-copy chmod command update live. You can also type an octal like 640 into the box to reverse it back into checkboxes. Everything runs locally in your browser.