Unix mode utility
Chmod 640 permissions explained
Mode 0640 gives the owner read/write and the group read-only access; others have none. Group membership determines who can read, so the label alone is not a confidentiality guarantee.
Live converter
Octal ↔ ls-style permissions
Exactly 3 or 4 digits from 0 to 7; 755 is normalized to 0755.
Exactly 9 characters, or 10 with only - or d as the type prefix.
Special bits
Special letters share the execute positions: s/S for owner or group and t/T for others.
ChmodCalc represents the traditional Unix mode-bit mask. It does not evaluate ACLs, umask, ownership, symlinks, recursive traversal or the suitability of a mode for a particular system.
GNU chmod nuance: on directories, plain 3/4-digit numeric modes can preserve existing setuid/setgid bits in some command forms. This calculator shows the requested bit mask, not guaranteed post-command filesystem state.
Current valid mask
Converted permission mode
Every bit explained
| Bit | Class | Octal value | State |
|---|---|---|---|
| Read | Owner | 0400 | On |
| Write | Owner | 0200 | On |
| Execute/search | Owner | 0100 | Off |
| Read | Group | 0040 | On |
| Write | Group | 0020 | Off |
| Execute/search | Group | 0010 | Off |
| Read | Others | 0004 | Off |
| Write | Others | 0002 | Off |
| Execute/search | Others | 0001 | Off |
| setuid | Special | 4000 | Off |
| setgid | Special | 2000 | Off |
| Sticky bit | Special | 1000 | Off |
Curated modes
Common permission masks
These presets are examples, not universal security recommendations. File type, ownership, application and deployment context determine whether a mode is appropriate.
rw-------Explain this moderw-r-----Explain this moderw-r--r--Explain this moderwx------Explain this moderwxr-x---Explain this moderwxr-xr-xExplain this moderwxrwxr-xExplain this moderwxrwxrwtExplain this mode